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B&W Turnoverball King Pin Adapter for Trailers with Inverted 5th-Wheel Hitches

B&W Turnoverball King Pin Adapter for Trailers with Inverted 5th-Wheel Hitches

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B and W Accessories and Parts - BWGNXA4000
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Insert this king pin into the hitch hole of your B&W Turnoverball underbed gooseneck hitch so that you can tow your trailer that has an inverted fifth-wheel hitch. Call 800-298-8924 to order B and W accessories and parts part number BWGNXA4000 or order online at etrailer.com. Free expert support on all B and W products. Guaranteed Lowest Price and Fastest Shipping for B&W Turnoverball King Pin Adapter for Trailers with Inverted 5th-Wheel Hitches. Accessories and Parts reviews from real customers.
  • All Info
  • Reviews (8)
  • Q & A (14)
  • Videos (2)
  • Photos
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B and W Accessories and Parts

  • Gooseneck Hitch
  • B and W

Insert this king pin into the hitch hole of your B&W Turnoverball underbed gooseneck hitch so that you can tow your trailer that has an inverted fifth-wheel hitch.


  • Trailer hitch adapter converts your B&W Turnoverball gooseneck hitch (sold separately) to an in-bed king pin
    • Allows you to tow your trailer with an inverted 5th-wheel hitch
  • Complete truck bed access when you're not towing
    • Just remove king pin and replace with upside down gooseneck ball or hitch plug (sold separately)
  • Square base prevents accessory from turning in hitch during hookup
  • Powder coated steel resists corrosion
  • Made in the USA


  • Overall diameter of plate: 8"
  • King pin diameter: 2"
  • Limited lifetime warranty

GNXA4000 B and W Turn Over Ball Gooseneck Hitch Inverted King Pin Accessory

Item # BWGNXA4000

California residents: click here

Video of B&W Turnoverball King Pin Adapter for Trailers with Inverted 5th-Wheel Hitches

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

Video Transcript for B&W Turnoverball King Pin Adapter Review

Speaker: Today we're going to be taking a look at the B&W Turnover Ball King Pin Adaptor. This is Part Number BWGNXA4000. This King Pin Adaptor is going to be the perfect solution for converting your B&W Turnover Ball Gooseneck Hitch into one that will accept the trailers that have the inverted fifth wheel on them. Typically, you're going to do this in a flatbed style truck, as you can see, we're in a normal bed truck. It's a special situation with this customer. Typically, these are going to work out great for going into the back of a flatbed that already has a gooseneck in it, that you'll be able to, then, backup to those really big hay trailers or anything that's got the inverted fifth wheel similar to a semi-trailer. Nice, heavy-duty steel construction, as you can see.

Just like with your B&W ball, it's going to be square, that way we have no risk of this turning, moving side to side and it's going to use the same connection style pin or the same pin that holds our goose neck in place. That's going to be the same pin that's going to hold our King Pin Adaptor in place. Just like when you want to remove your ball or stow your ball, we'll pull the lever there on the outside. With that release we'll just pull out our ball. The King Pin Adaptor will slide right down in. As you can see, it fits nicely just inside of our safety chain, hookups here, so we're not going to have to worry about any kind of interference or anything like that.

Then, we'll just release that handle. As you can see, we're nice and secure here, so our trailer is going to have a nice, sturdy connection point in your vehicle so you can haul it properly. That will complete today's look at the B&W Turnover Ball King Pin Adaptor, Part Number BWGNXA4000. .

Customer Reviews

B&W Turnoverball King Pin Adapter for Trailers with Inverted 5th-Wheel Hitches - BWGNXA4000

Average Customer Rating:  5.0 out of 5 stars   (8 Customer Reviews)

Insert this king pin into the hitch hole of your B&W Turnoverball underbed gooseneck hitch so that you can tow your trailer that has an inverted fifth-wheel hitch.

- BWGNXA4000

Another quality attachment from B&W to go with the best hitch design on the market! 713850

- BWGNXA4000

great price part was in original box packed by them this company is going to get more of my business as there prices are great and they ship quickly 616530

Great use it to tow a 36 ft enclosed race trailer
William - 04/03/2020


- BWGNXA4000

Took out my old hitch and bought this turn over attachment just the weight of it was obvious of how heavy duty it is! The finish and machining is excellent and compact. 588178

- BWGNXA4000

Very satisfied. 363732

Works great! No problems
Harry - 04/09/2018


- BWGNXA4000

good quality parts very happy 341290

- BWGNXA4000

Great product for my unique application, i bought an older gold rush trailer with an inverted fifth wheel and this made it as easy as dropping it in and going! 324027

- BWGNXA4000

We had gooseneck hitch in our truck and didn`t want to be out the money or time to change it to haul fifth wheel trailer so this product is great . Very well built and easy to use. 241100

- BWGNXA4000

very happy with service and part - than ks 143717


Ask the Experts about this B and W Accessories and Parts

  • How to Tow 5th Wheel Trailer with Inverted Hitch with Truck That Has Gooseneck Hitch
    I am sorry but we do not have a round shank gooseneck adapter to allow you to tow an inverted hitch 5th wheel trailer. We offer only the B&W Turnoverball King Pin Adapter # BWGNXA4000 that you mentioned and the # BWGNXA4025 which allows use of an inverted gooseneck hitch; both of these do have square shanks. But I do have another type of solution for you: a replacement 5th wheel pin box called a Goosebox. A Reese Goosebox is just like a standard 5th wheel king pin except it is designed...
    view full answer...
  • What is the Benefit of an Inverted 5th Wheel Hitch Head on a 5th Wheel Trailer
    One really big advantage to having and inverted 5th wheel hitch head on the trailer is that it is uncommon so that makes the trailer harder to steal. Another advantage is that its a little easier to hook up with a 5th wheel set up than a ball because the king pin can funnel into the hitch jaws. And on most 5th wheel set ups safety chains are not required but that can vary depending on the state so it is a good idea to just use them anyway. Since you already have a B&W Turnover Ball hitch...
    view full answer...
  • Outer Dimension of Square Tube for B&W Turnovrball King Pin Adapter # BWGNXA4000
    The base of the B&W Turnoverball King Pin Adapter # BWGNXA4000 is 2-1/2 inches by 2-1/2 inches square. This adapter was specifically designed to fit in a B&W Turnoverball gooseneck trailer hitch. I have linked the above mentioned product to this page for your viewing and purchasing convenience.
    view full answer...
  • Recommendation to Tow Trailer that has Inverted 5th Wheel Hitch with 2012 Ford F-250
    To tow a trailer with an inverted 5th wheel hitch using the already installed B&W Turnoverball underbed gooseneck hitch on your 2012 Ford F-250, you will just need to add the Turnoverball King Pin Adapter # BWGNXA4000. This will insert into the hitch hole of your B&W gooseneck hitch to convert it to an in-bed king pin, allowing you to tow your trailer. I have attached a short video demonstration on this product so you can see exactly how it works.
    view full answer...
  • Gooseneck Hitch Setup that Can Tow Gooseneck Trailer and Inverted Fifth Wheel
    I really wish there was a gooseneck to inverted fifth wheel adapter available for Curt hitches but the inverted fifth wheel setup is so rare there really isn't much of a demand for that type of adapter. The only setup I can recommend is the B&W Inverted fifth wheel adapter part # BWGNXA4000 but it will require you to replace your Curt gooseneck with a B and W part # BWGNRK1108.
    view full answer...
  • Weight Capacity of the B&W Turnoverball King Pin Adapter # BWGNXA4000
    The B&W Turnoverball King Pin Adapter # BWGNXA4000 shares the same ratings as the B and W Turnover Ball Hitches it is designed to fit like the part # BWGNRC962. This product has a 30k total trailer capacity and 7,500 pin weight.
    view full answer...
  • Size of Plate on B and W Inverted Fifth Wheel
    If you have a B and W Turnoverball hitch the inverted fifth wheel hitch # BWGNXA4000 is the only option we have and it has an 8 inch plate.
    view full answer...
  • Needing to Pull a Gooseneck Trailer with a 5th Wheel Hitch
    I have a solution for you, however, the B&W Turnoverball King Pin Adapter, # BWGNXA4000, is designed to drop into a B&W Underbed Gooseneck Hitch, like # BWGNRK1197, and tow an inverted 5th wheel hitch. In your case, if you are towing a gooseneck trailer with a 5th wheel hitch, your best option would be to use a Gooseneck-to-5th-Wheel Trailer Coupler, like # BD0289640300. Replacing the inner tube on the gooseneck with this adapter will allow you to connect the trailer to a 5th wheel...
    view full answer...
  • Is Location of B&W Gooseneck Adapter for Inverted 5th Wheel Hitches Compatible with 2019 Ford F250
    When Ford went to the aluminum beds, the position where that hole needed to be changed. Once B & W became aware of this change, they added an elongated hole to the # BWGNXA4000 to allow for the changed position of the retaining pin. This change was implemented in 2017, and all our current stock is of the updated kingpin adapter that will work perfectly with your 2019 Ford F250
    view full answer...
  • How to Tow Gooseneck Trailer with Inverted 5th Wheel King Pin with 2019 Ford F-250 Factory Pucks
    I do have some potential solutions for you, however there's not an adapter or system available that will allow you to pull a trailer with an inverted 5th wheel head behind your Ford F-250 that's equipped with the factory puck system. You could potentially remove the factory puck system but this is going to require some pretty significant modifications. I might even check with a local Ford dealer to see how this can be done and to make sure it's not going to affect the integrity of the...
    view full answer...
  • Can Truck with B and W Turnoverball Gooseneck Hitch Tow Trailer with Inverted Fifth Wheel
    B and W offers a king pin adapter designed to fit their Turnoverball hitches like the part # BWGNRK1108 that you referenced. For that you'd want the part # BWGNXA4000. You should note that this is for inverted fifth wheel setups and not standard fifth wheel towing. B and W does offer standard fifth wheel hitches to fit the Turnoverball hitches as well like the Companion part # BWRVK3500.
    view full answer...
  • Parts Needed to Tow a 5th Wheel Trailer with Inverted Pin Box with a 2018 Chevrolet Silverado 2500
    I do have a solution for you, but we typically recommend going with a sliding 5th wheel hitch when towing a 5th wheel trailer with a truck that has a bed shorter than 8 feet. For your 2018 Chevrolet Silverado 2500 with a 6-1/2 foot bed I recommend installing the B&W Turnoverball Underbed Gooseneck Trailer Hitch # BWGNRK1016 and then using the B&W Turnoverball King Pin Adapter # BWGNXA4000. This adapter allows you to tow your trailer that has an inverted 5th wheel pin box and can easily...
    view full answer...
  • How to Tow 5th Wheel Hitch w/ 2008 Ford Super Duty with In-Bed Kingpin
    The in-bed king pin is kind of an oddity that isn't terribly common. How to proceed will depend on whether you'll need to continue to use the in-bed kingpin. If you will, your best bet would be to remove the existing kingpin and install a B&W Turnover Ball, part # BWGNRK1108. When you need to tow the trailer with the inverted fifth wheel hitch, use the # BWGNXA4000 adapter. When you need a standard non-inverted fifth wheel hitch use # BWRVK3500-5W. Or if you have a short bed truck,...
    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...
    view full answer...

Do you have a question about this Accessories and Part?

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Info for this part was:

Expert Research:
Jackie C
Expert Research:
Mike L
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
Adam R
Written by:
Lindsey S
Updated by:
Adele M
Updated by:
Sarah W
Updated by:
Kristina F
Installed by:
Cole B

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