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Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate - Weld On
Buyers Products

Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate - Weld On

Part Number: 337KP20050
In Stock
$84.88
Retail:$116.54
You Save: 27%
5th Wheel Pin Box
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Buyers Products 5th Wheel Pin Box - 337KP20050

Highlights

  • Forged AISI 8630 Steel: Provides unmatched strength and reliability for fifth wheels.
  • Heat Treated Hardness: Withstands 302-363 BHN and 150,000 PSI ultimate strength.
  • Weld On Design: Ensures a secure, permanent installation with a 1/2" bolster plate.
  • Made in the USA: High-quality construction you can trust.
  • Standard 2" King Pin: Compatible with semi-tractors and RVs, ensuring versatility.
  • Plain Finish: Offers a straightforward, timeless look without additional coatings.

Features to know about

Built for Maximum Durability: Forged AISI 8630 Steel

When you’re dealing with serious towing, durability is key. The Buyers Products 2" Forged SAE Trailer King Pin is made from AISI 8630 steel, making it ultra-strong and reliable. It's heat treated for a hardness rating of 302-363 BHN and boasts a 150,000 PSI ultimate strength. This means it can withstand the rigors of heavy-duty towing, ensuring confidence and safety every time you hit the road.

Silky Smooth Maneuvers: Standard 2” King Pin

Whether you're navigating city streets or open highways, having a standard 2-inch king pin makes a world of difference. It's compatible with both semi-tractors and RVs, making connecting and disconnecting straightforward and tension-free. With its standard size, hooking up your fifth wheel is consistently hassle-free.

Tailored Fit for Seamless Performance: 1/2" Thick Bolster Plate

The King Pin comes with a 1/2-inch thick bolster plate, aligning perfectly with heavy-duty needs. This means you get a rock-solid union between your truck and trailer, reducing unnecessary movement and wear over time. If your setup demands a reliable partner, this King Pin's thickness ensures uniform stability for a stress-free towing experience.

Effortless Installation with the Right Tools: Compatible Welding Materials

No need to guess what you’ll need for the best mount. Use a 5/32" low hydrogen welding rod or .045" low carbon wire to securely install this king pin. This straightforward compatibility means even large-scale repairs or replacements don’t feel daunting, letting you focus on getting back on the road quickly and safely.

Adaptable to Various Applications: Versatile Boost Plate Options

From campers to commercial vehicles, adapt this king pin to your specific needs. The king pin is not just a one-size-fits-all solution; its design accommodates different bolster plate thicknesses like 1/4", 5/16", 3/8", and 1/2". This level of customization ensures each application receives precisely what’s needed for optimal performance and safety.

Perfect Partner for Trailer Mods: Plain Finish for Customization

The plain finish of this king pin isn't just aesthetically neutral; it’s an opportunity. For those who love to customize and adapt, the plain finish allows for easy painting or coating to match your trailer’s style and needs. This makes it the ideal choice for enthusiasts looking to blend utility with personal flair.

KP20050 Buyers Products 2 Inch Forged SAE Trailer King Pins With 1/2 Inch Bolster Plate - Weld On




California residents: click here


Video of Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate - Weld On

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.




Video Transcript for Buyers Products Fifth Wheel King Pin - Universal King Pin - 337KP20050 Review

Speaker 1: Today we're taking a look at a two-inch Forged SAE Trailer King Pin. The Trailer King Pin provides strength and reliability in coupling your fifth wheel. It's forged from AISI8630 steel and heated treated to maintain a hardness 302-363BHN and 150,000 PSI in ultimate strength. Now, the King Pin has a half-inch thick bolster plate. That's the measurement of this portion right here. From this plate to the edge of the lift, that's a half inch.

It's made from forged steel and has a plain finish, and it's a weld on installation. The overall diameter of the unit is eight inches from very bottom to very top. I'll leave that flat edge up there, and I'll measure up to that. That's going to give us a measurement of about four and a half inches. Then, if we take a measurement from bottom, to the bottom of this plate here, that's going to give us a measurement of about three and 13/16 to three and 7/8 inches.

Right in that area.Now, this portion here, this has a diameter edge to edge of two and 13/16 inches. This right here has a diameter of two inches, and then the base has a diameters of three inches. Again, nice durable forged steel construction, and the product's made in the U.S.A. That's going to do it for today's look at the two-inch Forged SAE Trailer King Pin.

Customer Satisfaction Score:

Ratings & Reviews

4.8

77 reviews

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Fast good service



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Great product and arrived quickly



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Great thanks



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USA made, excellent



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Good job



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Part ordered was exactly what was needed and delivered on time without incident.


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See what our Experts say about this Buyers Products 5th Wheel Pin Box

  • Does Curt E16 5th Wheel Hitch Fit Curt Universal Base Rails
    They are! The Curt hitch and base rail kit you asked about are 100 percent compatible: - Curt E16 5th Wheel Trailer Hitch # C16115 - Curt Universal Fifth Wheel Base Rails with Installation Kit # C16200 This will give you industry-standard base rails, which the E16 hitch will mount right into so you can tow your 5th wheel trailer.
    view full answer...
  • When to Replace a Trailer King Pin Based on DOT Regulations
    The Fifth Wheel Trailer King Pin # 337KP20050 is 2 inches diameter where the jaws of the 5th wheel hitch will connect. Typically the max wear on a king pin is .080 of an inch with a minimum diameter of 1.920 before manufacturers recommend replacement. DOT says the max wear is .125 of an inch with a minimum diameter of 1.875. I did not find any specs for non-commercial trailer king pin requirements from the Federal Government. You can find all the federal information for commercial...
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  • Can A Fifth Wheel Be Used With An Inverted Fifth Wheel On A Trailer Using A Fabricated Dual King Pin
    This is the first time I have heard of the issue you are describing. It sounds like there is an inverted fifth wheel hitch on the trailer you are trying to deal with. The best solution I could recommend would be to remove the inverted fifth wheel on the trailer and install a king pin like part # 337KP20050. I am not certain about the legality of the dual fifth wheel hitches being used with a fabricated dual king pin. You will need to check with the Department of Transportation in the...
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  • Why Do King Pin Replacements Have Different Bolster Thicknesses
    King pins can be found on a variety of different trailer types; 5th wheel, gooseneck, RVs, campers, lawncare, excavating, and car haulers just to name a few. So if you're just replacing the king pin you will want to use one that has a matching bolster plate thickness: 1/4" - # 337KP20025 5/16" - # 337KP20031 3/8" - # 337KP20038 1/2" - # 337KP20050 Attached is a review video for you to check out.
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  • Recommended Gooseneck Hitch Ball to 5th Wheel Trailer Adapter
    The Fifth Wheel Trailer King Pin # 337KP20050 is a weld on king pin to make your trailer compatible with 5th wheel hitches. If you want the gooseneck trailer to 5th wheel king pin adapter, you can use the Ram Gooseneck to 5th Wheel Trailer Coupler Adapter Inner Tube - Square # KPG5-Q30IP or round # KPG5-R30IP. If you have a gooseneck hitch installed in your truck and you have a 5th wheel trailer, then you will want the Demco Recon Gooseneck-to-5th Wheel Trailer Hitch Adapter # DM8550045...
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  • Troubleshooting Reese Low-Profile 5th Wheel Trailer Hitch # RP30054 That Doesnt Fit Camper Kingpin
    The Reese Low-Profile 5th Wheel Trailer Hitch - Dual Jaw - 30,000 lbs # RP30054 is confirmed to fit the standard 2 inch diameter king pins. Use a digital caliper like # PTW80157 to measure the inner diameter of the closed jaws and the external diameter of the king pin. I've attached a photo of the detailed dimensions of a standard king pin to help. If the hitch is the issue, then you will need to return it for a properly functioning model as there is no adjustment of the hitch jaws. If...
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  • Can a 5th Wheel Hitch Rated for Recreational Use be Used for a Commercial Trailer
    It is possible that you can tow a commercial trailer with a 5th wheel hitch rated for recreational use but it is not really a good idea for an extended period of time. The first issue as to why it might not be a good idea is because of the kingpin dimensions. The standard kingpin used on recreational trailers is 2" diameter. This is also the size used on most commercial trailers as well but they could utilize a 3-1/2" diameter kingpin so you will need to check this beforehand. If it does...
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  • Correct Welding Material For Installing Buyers Products 2" Forged SAE Trailer King Pin
    It looks like you need either a 5/32" low hydrogen welding rod or .045" low carbon wire in order to properly install the Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate # 337KP20050. I'm not going to pretend to start to know a thing about welding, but an experienced welder who has done this type of work before will know which option is best for you. If you haven't done something like this before then I highly recommend having a professional check the work when you're...
    view full answer...
  • Weld Installation Universal King Pin Replacement
    The Fifth Wheel Trailer Universal King Pin # 337KP20050 has welding procedures in accordance with the American Weld Society. They don't have specific specifications, so I recommend utilizing a professional welder for installation to ensure the weld will be the correct strength for your trailer.
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  • Bolt Size Needed For Buyers Products 2 Inch Forged SAE Trailer King Pin 337BKPT809B
    The bolts do not come with the Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate - Bolt On # 337BKPT809B. So I did check with the manufacturer, Buyers Products, and they told me the bolts needed to be 1 inch long x 1/2 inch. As far as procedure, there isn't one I can offer as it will differ depending on the application and is a project for professional fabricators. As for which is better, this bolt-on has the exact same specs as the weld-on # 337KP20050 king pin...
    view full answer...
  • 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...
    view full answer...
  • Should King Pin Plate on Fifth Wheel Trailer be Level
    Yes, you would want the king pin plate on a fifth wheel trailer to be as level as possible. This will help make connecting to the hitch easier but most hitches have tilting capabilities in the heads so if it's not perfectly level it will still be okay.
    view full answer...
  • Maximum Amount of Wear 5th Wheel Trailer King Pin Before Replacement
    Typically the max wear on a king pin is .080 of an inch with a minimum diameter of 1.920. DOT says the max wear is .125 of an inch with a minimum diameter of 1.875. When new the king pin will have 2 inches of diameter. See the image I made for you showing the dimensions of a weld on king pin.
    view full answer...
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  • Can I Tow a 5th Wheel Travel Trailer with a Semi Truck or 18-Wheeler
    The king pin dimensions can be the same between fifth wheel trailers and large commercial trailers. Both types of trailers often use a standard 2 inch king pin although semis sometimes have a 3-1/2 inch. As long as your truck fits a 2 inch king pin it can work. Semi trucks were not technically designed to tow camping style fifth wheel trailers, so there are several factors that you will want to take into consideration before attempting to tow. First, you will want to make sure the truck...
    view full answer...
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  • Are There Universal-Fit Replacement King Pins Available
    If you're wanting to only replace the king pin you'll need to measure the bolster plate hole and use a weld-on king pin like part # 337KP20050. This specific part has a 3" bolster hole diameter. As long as the bolster hole is large enough for the replacement and the pin box is still in good condition then you can have a qualified welder weld the new king pin on. If you'd prefer to just replace the entire pin box then we'll need to first determine the bolt pattern for your current pin...
    view full answer...
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  • Recommended King Pin for Custom Pin Box
    We do not custom engineer pin boxes as there is a lot of testing required to ensure a fit as well as determine compatibility. If you want to have a pin box custom made by a local welder to meet your specifications, then you can use the Buyers Products # 337KP20050 to give you the standard king pin that will work with 5th wheel trailer hitches.
    view full answer...
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  • Availability Of A King Pin For 5th Wheel Trailer
    We do offer just the king pin like the Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate # 337KP20050 which gives you the standard 2" king pin for use with a 5th wheel hitch. It is a good idea to have a qualified welder install the king pin, as the welds need to be sound to support the weight of the trailer. I included a video of the Buyers # 337KP20050 for you to take a look at.
    view full answer...
  • Does 2009 Dodge Ram 2500 Short Bed Need Slider Hitch Towing 2014 Keystone Sprinter 314 FWRLS
    In general a sliding hitch is needed when towing a fifth wheel trailer with a truck that has a bed shorter than 8 feet. There are scenarios where a slider hitch isn't needed though like if the trailer happens to have a tapered nose. I looked up your 2014 Keystone Sprinter 314 FWRLS and the nose of it is tapered the pin box is extended and since your short bed truck is a bit longer at 6.5 foot (a lot are shorter than that) I'd think you'd most likely not need a slider. If it were me I...
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  • Will the Buyers Products 2" Forged SAE Trailer King Pin Fit a Semi Tractor
    The Buyers Products 2" Forged SAE Trailer King Pin with 1/2" Bolster Plate part # 337KP20050 should work just fine on a semi-tractor since both they and RV's use a standard 2" diameter kin pin.
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Do you have a question about this 5th Wheel Pin Box?


Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jameson C
Expert Research:
Jameson C
Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Written by:
Kristina F

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