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  1. 5th Wheel Gooseneck Adapter
  2. etrailer
  3. Gooseneck Trailer to 5th Wheel Hitch
  4. Replaces Inner Tube
  5. Not Shock Absorbing
  6. Adapts Trailer
Gooseneck to 5th Wheel Trailer Coupler Adapter - Inner Tube - Square - 25,000 lbs
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Gooseneck to 5th Wheel Trailer Coupler Adapter - Inner Tube - Square - 25,000 lbs

Part Number: KPG5-Q25-IP
In Stock
$196.93
Retail:$207.43
You Save: $10.50
5th Wheel Gooseneck Adapter
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etrailer Installation
We'll connect you with nearby partnered installers who know this exact setup.
King pin coupler allows you to pull your gooseneck trailer with a fifth-wheel hitch. The height easily adjusts to fit your application. Square inner tube is included. 1-800-940-8924 to order etrailer 5th wheel gooseneck adapter part number KPG5-Q25-IP or order online at etrailer.com. Free expert support on all etrailer products. Great prices and Fastest Shipping for Gooseneck to 5th Wheel Trailer Coupler Adapter - Inner Tube - Square - 25,000 lbs. 5th Wheel Gooseneck Adapter reviews from real customers.
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etrailer 5th Wheel Gooseneck Adapter - KPG5-Q25-IP

Highlights

  • Tow Your Gooseneck Trailer with a Fifth Wheel Hitch: Converts your gooseneck coupler to a 2" industry-standard king pin so you can use a fifth wheel hitch for towing.
  • 25,000 lbs. Load Capacity: Rated to handle heavy equipment, livestock, or large loads without sacrificing strength.
  • Adjusts for Proper Trailer Height: Offers 8" of vertical adjustment (2-11/16" hole spacing) so you can level your trailer easily.
  • Fits Standard 4" Square Outer Tubes: Designed as an inner tube replacement for most standard square gooseneck couplers.
  • Built for Long-Term Durability: Heavy-duty steel construction is SAE J2638 compliant for strength and reliability.
  • Simple, Secure Attachment: Uses a load-bearing pin (GCPN-PIN, sold separately) through 13/16" pin holes for solid connection.

Features to know about

Switch from Gooseneck to Fifth Wheel Towing: Standard 2" Kingpin Connects with Ease

When you need to pull a gooseneck trailer using a fifth wheel hitch, this adapter makes it easy. It replaces the inner tube on most standard 4" square gooseneck couplers and adds a 2" industry-standard kingpin to connect with your fifth wheel plate. It’s an ideal setup when you want to use your existing fifth wheel hitch instead of installing new gooseneck hardware.

Strong and Simple: Rated for 25,000 lbs and Built from Steel

This square-tube adapter is made from sturdy steel and rated for up to 25,000 lbs. It meets SAE J2638 standards for strength and reliability, so it’s built to handle serious towing without compromise. The heavy-duty construction gives you confidence whether you’re hauling equipment, livestock, or heavier trailers.

Features and Construction

Heavy-duty black steel gooseneck trailer coupler with adjustable inner tube and 2-5/16-inch ball socket, shown on clean white background.

Fine-Tune Your Fit: 8" of Vertical Adjustment

Every trailer setup is a little different, so having the ability to dial in the right height matters. The tube gives you an 8" range of vertical adjustment with pre-drilled holes spaced 2-11/16" apart center-to-center. That makes it easy to level your trailer and hitch connection so everything rides smooth and secure.

Easy Setup: Fits Standard Square Outer Tubes

The 4" square inner tube slides into most standard outer coupler tubes for a snug, straightforward install. The pin holes have a 13/16" diameter and can be secured with a load-bearing pin such as part #GCPN-PIN (sold separately). The adapter measures 9-7/8" long by 10" wide at the plate and has an overall length of 34-3/4", giving you a clean fit that’s simple to line up and lock in place.

Specs

Dimensions

  • Tube width: 4"
  • Range of vertical adjustment: 8"
  • From center of hole to center of hole: 2-11/16"
  • Plate dimensions: 9-7/8" long x 10" wide
  • Pin hole diameter: 13/16"

Weight and Capacity

  • Weight capacity: 25,000 lbs

Warranty

  • Warranty: 1-Year

KP5G-Q25IP Ram Gooseneck to 5th Wheel Trailer Coupler Adapter Inner Tube - Square - 25,000 lbs

Replaces KP5G-Q25-IP





Customer Satisfaction Score:

Ratings & Reviews

4.7

904 reviews
5 Stars
(747)
4 Stars
(86)
3 Stars
(30)
2 Stars
(18)
1 Star
(23)
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by:
Fast shipping and works perfect
by:
Well worth the money. No paint which was fine. I did have to drill holes larger for my application. Far better than having to jack up and down my gooseneck all the time.
Eric profile picture

Eric

5/22/2026

Still great.

by:
Good price and fast shipping couldn't ask for better
by:
The king pin adapter works great and I won't have to switch back-and-forth between gooseneck ball and fifth wheel hitch anymore. I found the best price at the etrailer.com .
by:
Well built product. Only problem is the holes were too small for my locking pin. Just used a die grinder to open them up a little and fit great. I did paint it also, came bare.
by:
Un coated not impressed
by:
Shipped with great timing. Made with great quality.. installed in about 15 minutes. I have used the round one and the square one and they both work fantastic.
by:
Worked great
by:
Quality manufacturing. I have a 1989 gooseneck car hauler with a 4 1/2 inch OD square tube and I'm changing it over to a king pin. This is a 4 inch OD and it fits perfectly inside my existing tubing. The holes aren't the same size as my original 4 1/2 inch but that's an easy fix. I can't wait to be able to tow my 5th wheel and my car hauler without having to switch from king pin to gooseneck ??????
Opa profile picture

Opa

9/27/2017

Perfect, Works as good as new.

by:
The bottom hole is not low enough.problem have drill a enough hole
by:
Had to cut it down to make it fit but it works good
by:
Installation photo
by:
Worked perfect on my square tube gooseneck to convert it over. Adjustment holes and everything lined up like it should and seems to be well built.
by:
Everything is working fine. Product fit great and pulling like a champ. Great packaging job too.
by:
This thing works. No hassles with hitching and I don't have to swap out my fifth wheel from the truck (which pulls the camper too) to use the equipment trailer.

The fifth wheel is easier to hitch and disconnect than the ball hitch that it replaced.
I see no disadvantages, except that my neighbors can't just borrow my trailer.
by:
My pickup engine went down being unable to pull a my gooseneck with a ball application I ordered your 4 in kinpin adapter for a gooseneck trailer as you can see in the pictures it pinned in perfectly with no trouble at all with your adapter im able to get my trailers moves while repairs are made and with it i'll just have to use the fifth wheel hitch for the pickup witch is much more easy to use than a goose ball
by:
This gooseneck to 5th wheel adapter was an excellent decision, hooking up my equipment trailer is now as piece of cake.
by:
Installed easy. It has allowed me to use my larger truck and retain the ability to swap back if needed.
by:
Looks well built holes was too snall had to drill them out
by:
I use this to pull my gooseneck flatbed with my road tractor. It works fine on both my trucks.
by:
I could not be more pleased with this product I ordered and with etrailer. I was in a bind and needed this adapter asap, and etrailer received my order, got it packaged, had it shipped and at my door within 24 hours! Another highlight is that I was expecting to pay a good dollar amount for overnight service, but, etrailer shipped it overnight for me at no additional charge. I will definitely use etrailer for all my trailer needs and will recommend them to anyone.
Thank you etrailer for making my stressful situation less stressful.
by:
Has held up well to the wear and tear of my overloaded trailer. Very good quality item and well built.
by:
I am very happy with the product. Is very good quality and fit the trailer perfect. And price was very fair. Website was also very easy to use.

Keep it up.
by:
I can see the 5th wheel hitch in the rear view mirror which makes it easier to hook up versus the gooseneck.
by:
Fits like a glove.. Perfect fit, converted a gooseneck to 5th wheel. Took 1 minute and done..
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See what our Experts say about this etrailer 5th Wheel Gooseneck Adapter

  • What is Outer Diameter of Gooseneck to 5th Wheel Trailer Coupler Adapter - Inner Tube # KPG5-Q25-IP
    Hey Ray, the Gooseneck to 5th Wheel Trailer Coupler Adapter - Inner Tube # KPG5-Q25-IP has an outer tube diameter that measures 4 inch by 4 inch. There might be some minor variances that could be around what you mentioned but it was intended to be 4 inch by 4 inch.
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  • Square Gooseneck to 5th Wheel Coupler Adapter For Big Tex Trailer
    By king pin sleeve I believe you are referring to a gooseneck to 5th wheel coupler adapter, and there is one for a square inner tube: - Gooseneck to 5th Wheel Trailer Coupler Adapter - Inner Tube - Square - 25,000 lbs # KPG5-Q25-IP The # KPG5-Q25-IP has a 4 inch tube width so it fits standard square gooseneck outer tubes.
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  • Does Head of Fifth Wheel Hitch Need to Lock Out When Using Gooseneck to 5th Wheel Adapter
    You would not have to block out the fifth wheel plate of your hitch to prevent movement if you were use a fifth wheel to gooseneck adapter # KPG5-Q25-IP. The head of the hitch can move when using adapters like this.
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  • Square Tube Gooseneck Coupler Adapter Recommendation
    We offer 2 square tube gooseneck-to-fifth-wheel coupler adapters, the Redline Coupler Adapter, # KPG5-Q25-IP, and the Bulldog Coupler Adapter, # BD0289650300. These are quality couplers that would do an excellent job. If I were choosing one of these couplers, I would go with the Bulldog coupler because it has a wider bottom plate similar to a fifth wheel pin box that will make more contact with the fifth wheel hitch. It also has a small curved lip at the front of the plate making it easier...
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  • Recommended Adapter to Switch my 4" Square Gooseneck to a Fifth Wheel
    The Bulldog Gooseneck-to-5th-Wheel Trailer Coupler Adapter part # BD0289650300 will do a great job switching your current gooseneck over to a fifth wheel. It has an outer tube diameter of 4" and will slide right into your current 4" square outer tube. To verify this ensure your outer tube measures 4" inside to inside. The Gooseneck to 5th Wheel Trailer Coupler Adapter part # KPG5-Q25-IP is also a good replacement that will accomplish your goal. It is a more cost effective option. Between...
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  • Pulling Gooseneck Trailer w/ 5 ton Truck w/ Custom Fold-Away 5th Wheel Hitch
    If the fifth wheel hitch is mounted using industry-standard 5th wheel rails (see photo), you can simply remove the existing fifth wheel, and mount an adapter like # 16055. If your gooseneck trailer has a removable coupler, we offer some king pins that will actually slide into the square or round tube the coupler fits into. For a round 4 inch diameter tube, use # KPG5-R25-IP or # KPG5-Q25-IP for a square tube that measures 4 inches square. If you have some other set up, please reply with...
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  • Recommended Square Tube Gooseneck to 5th Wheel King Pin Adapter
    It sounds like you have a gooseneck like the Atwood Gooseneck Trailer Coupler AT75401. For an adapter to kingpin, I recommend the Bulldog Gooseneck-to-5th-Wheel Trailer Coupler Adapter - Inner Tube - Square - 30,000 lbs # BD0289650300 or the # KPG5-Q25-IP. Both measure 4 inches outer diameter to fit inside a tube 4-1/2 inches outer diameter. Another option is to use the Bulldog Gooseneck-to-5th-Wheel Trailer Coupler Adapter - Square - 30,000 lbs # BD0289590300. This will only be needed...
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  • Recommended 5th Wheel Sliding Hitch For 2015 Ford F-250 4x4 and Gooseneck Trailer
    The Demco Hijacker Autoslide 5th Wheel Trailer Hitch w/ Slider - Single Jaw - Above Bed - 18,000 lbs # DM8550034 is an excellent hitch for your 2015 Ford F-250 Super Duty 4x4. I personally think this is the best hitch available for short bed trucks because it has the autoslide ability to give you the clearance you need for safe turning. This hitch connects to industry standard 5th wheel rails, so I recommend the Demco Hijacker Premier Series Above-Bed Base Rails and Custom Installation...
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  • Picking Out Gooseneck to Fifth Wheel Adapter that Could Fit Diamond C FMAX 212 HDT Trailer
    Most likely the Ram Gooseneck to 5th wheel adapter part # KPG5-R30IP is what you'd need as this fits most gooseneck hitch tubes that have an inner tube diameter that is 4 inches. If you have a different setup let me know. Another popular setup is 4 inch square tube like with the part # KPG5-Q25-IP. I attached a link to a page that has all of the adapters we have for you to check out as well.
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  • Gooseneck to 5th Wheel Trailer Coupler Adapter For Demco Autoslide 5th Wheel Hitch
    For a gooseneck to 5th wheel trailer that you can use, the recommended option simply depends on the shape of your gooseneck tube, whether it is square or round. The inside dimension of a square gooseneck tube should be 4 inches, while the inside dimension of a round gooseneck tube should be 4 inches in diameter. If that's what you have you can use one of the following: - Round Tube: Gooseneck to 5th Wheel Trailer Coupler Adapter # KPG5-R25-IP - Square Tube: Gooseneck to 5th Wheel Trailer...
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  • Will Reducing Air Pressure in Suspension Air Bags Reduce Sway on a 5th Wheel Trailer
    You can experiment with different amounts of air pressure in the air bags to get to the best ride quality. More pressure would make the bag stiffer and there would be less trailer at the front of the trailer (mostly vertically but also some side to side) and rear of the truck. A bag with less pressure would have more give and could be more of a cushion and absorb some of the force that is causing the sway. When the trailer does start swaying you will want to reduce speed and keep the...
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  • Gooseneck Trailer Hitch Ball with Offset for Fifth Wheel Rails
    We do have a solution for you, though there is not a Gooseneck to 5th Wheel Trailer Coupler Adapter such as # KPG5-Q25-IP which has an offset. Since you are looking to use your gooseneck trailer and have a fifth wheel hitch I recommend checking out the Curt Above-Bed Gooseneck Trailer Hitch for Fifth Wheel Rails # 16055 which will give you a 3 inch offset. This will work with standard above-bed 5th wheel base rails from Curt, Reese, Draw-Tite, Hidden Hitch, and Valley. It has a 25,000...
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  • Will Gooseneck to Fifth Wheel Adapters Fit a Fifth Wheel Hitch on a Kenworth Over the Road Tractor
    The most common size for a kingpin that fits a fifth wheel hitch is 2 inches in diameter. We have checked the kingpins on some of the truck trailers here on our lot and they measured 2 inches. I would recommend to measure the opening on your fifth wheel hitch with the jaw(s) closed to see if your Kenworth tractor will fit a 2 inch diameter kingpin. The gooseneck to fifth wheel adapters will come in either a square tube design or a round tube design. You will need to choose the adapter...
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  • Fifth Wheel Adapter Options Other Than King Pin to Gooseneck Ball
    We don't have a 2 inch receiver application, but we do have the B&W Turnoverball King Pin Adapter for Trailers with Inverted 5th-Wheel Hitches # BWGNXA4000 which is a 2-1/2 inch outer measurement on the solid square. We also have the Fifth Wheel Trailer King Pin # 337KP20050 with no connection on the backside if you need to make a custom adapter If you are looking for a gooseneck to king pin connection, we have the Gooseneck to 5th wheel adapter inner tube # KPG5-Q25-IP which has a 4...
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  • Do You Have Adapters to Convert a Gooseneck Trailer to a Fifth Wheel
    Yes, we have a couple different solutions that could solve your problem. Since you have a fifth wheel with rails already in your bed, I would suggest using a Gooseneck plate built for fifth wheel rails like Curt part # 16055. If you will be towing other fifth wheel trailers and need to keep your fifth wheel on the truck at all times and do not want to pull the fifth wheel on and off, we do have adapter tubes. If you have a round gooseneck coupler with a 4 inch outer diameter, you could...
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  • Troubleshooting Voltage Drop on Brake Output Circuit When Brakes are Wired Up on Trailer
    It sounds like the ground of the assemblies isn't attached properly or to the correct location. Most of the time you can just run the ground wire of the assemblies to the trailer frame but if it's an aluminum frame trailer you may need to run a jumper wire from it back to the main ground of the trailer wiring harness.
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  • Info Needed to Determine if Gooseneck to 5th Wheel Trailer Coupler Adapter Can Fit Trailer
    The Gooseneck to 5th Wheel Trailer Coupler Adapter # KPG5-Q25-IP that you referenced is not a trailer brand specific fit. It can basically fit any trailer that has an outer gooseneck tube that has an inner dimension of 4 inch by 4 inch. The pin hole diameter is also 7/8 of an inch. If that would work on your trailer this would fit and work great.
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  • Adjustable Gooseneck To 5th Wheel King Pin Assembly
    We don't have one that says anything that is compatible with a crank adjuster, but we do have the tube adapters you mentioned. If you have a round tube, I recommend the Gooseneck to Fifth Wheel Trailer Adapter # BD0289640300 which has a 4 inch outer diameter or for the square tube the Gooseneck to Fifth Wheel Trailer Adapter - Square, # KPG5-Q25-IP. This is 4 inches square outside measurement. If you are looking for a hitch that works in standard 5th wheel rails and works with a gooseneck...
    view full answer...
  • Is There a Gooseneck to 5th Wheel Trailer Coupler Adapter for Square Gooseneck Couplers
    Yes, there is a Gooseneck to 5th Wheel Trailer Coupler Adapter for square couplers, the part # KPG5-Q25-IP which has a 4" wide square tube and is designed for a 4-1/2" wide coupler. Therefore, if your outer tube is 4-1/2" then this will work great but if it's 4" then we would not have an option for this without also replacing the outer tube for which you'd need the Gooseneck to 5th Wheel Trailer Coupler Adapter part # KPG5-Q30.
    view full answer...
  • What is the Diameter of the Tube on the KPG5-Q25-IP Ram Gooseneck Adapter
    The Gooseneck to 5th Wheel Trailer Coupler Adapter # KPG5-Q25-IP is a 4" x 4" tube, so as long as your outer tube is designed to fit that width you can use this as your gooseneck to 5th wheel. If you measure the inside diameter of your outer tube and find you've got something different just let me know and I can let you know what options we have for you that will work.
    view full answer...
  • Hitch Pin Recommendation for the Gooseneck to Fifth Wheel Adapter # KPG5-Q25-IP
    The hitch pin that I recommend for the Gooseneck to Fifth Wheel Adapter, # KPG5-Q25-IP, is the Hitch Pin, # GCPN-PIN. This hitch pin has a diameter of 3/4 inch and a length of 6 inches and it will work with the coupler adapter that you referenced. I verified the compatibility with my contact at Redline.
    view full answer...
  • Can a Gooseneck to 5th Wheel Trailer Coupler Adapter Be Used with Bolts Instead of Locking Pins
    As long as the inner diameter of the outer tube on your gooseneck trailer has a 4" wide opening then the Gooseneck to 5th Wheel Trailer Coupler Adapter part # KPG5-Q25-IP will still work for you. We do not have anything specifically designed for your trailer but the adapters are very universal with just slight modifications. On the adapter there are four 7/8" diameter pre drilled holes for vertical adjustment. The adjustment holes can be secured by either a locking pin or bolt. If the...
    view full answer...
  • What Size King Pin On A Gooseneck Adapter Is Needed To Fit The Pro-Series Hitch, # PS30094
    The Reese 5th Wheel Trailer Hitch with Square Tube Slider, # RP30051, has a 16,000 lbs. gross towing weight capacity. It will accept a industry standard 2 inch king pin. It has 10 inches of slider travel to give you clearance between your truck and the trailer. This fifth-wheel trailer hitch will not fit trucks with beds shorter than 6 feet. It also will not fit trucks with flareside/stepside beds. A minimum 13 inches extended trailer pin box is recommended. We do have a couple adapters...
    view full answer...
  • Weight Capacity of etrailer Goosesneck to Fifth Wheel Adapters # KPG5-R30IP and # KPG5-Q25-IP
    The etrailer fifth wheel adapters part # KPG5-R30IP and # KPG5-Q25-IP do not have vertical weight capacities. As long as the overall trailer capacity figure is not exceed of either you'd be safe. The part # KPG5-R30IP has a 30k capacity and the # KPG5-Q25-IP is rated for a 25k trailer.
    view full answer...


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Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Jameson C
Expert Research:
Jameson C
Employee Wilson B
Updated by:
Wilson B
Employee Mike S
Updated by:
Mike S
Employee Amanda M
Written by:
Amanda M

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