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If you’ve got a gooseneck trailer but want to pull it with a fifth wheel hitch, this adapter makes that switch clean and easy. The Gooseneck to 5th Wheel Trailer Coupler Adapter – Round – 30K connects your gooseneck trailer to your fifth wheel setup without extra hardware or complicated modifications. It fits most standard 4" round gooseneck outer tubes and gives you a standard king pin connection so it locks solidly into the hitch jaws.
This heavy-duty coupler adapter is built to handle big loads. With a 30,000-lb weight capacity and .275" wall thickness on the inner tube, it’s a tough piece of gear for heavy equipment, livestock, or large trailers. The welded belly band around the lower section adds structural reinforcement for extra strength under full load.
Getting your trailer level is key for safe towing. The adapter has an 8" range of vertical adjustment with holes spaced 2-11/16" center-to-center, so you can dial in the right height for your setup. The overall tube length is 29" from top to plate, with the first adjustment hole 14" down from the top. That flexibility makes it easy to match your trailer to your fifth wheel hitch height.
Made from sturdy steel and tested to SAE J2638 standards, this adapter gives you a reliable fit and secure pull every time. The round inner tube slides into your existing gooseneck outer tube and locks in place with a load-bearing safety pin (sold separately). The plate measures 9-7/8" long by 10" wide, offering a stable platform for your fifth wheel king pin connection.
To protect your hitch head and keep things quiet during travel, you can use a standard 10" lube plate with this adapter. It helps reduce friction and wear between the hitch and the adapter plate so your setup stays smooth and long-lasting.
Customer Satisfaction Score:
99% were satisfied with this product
1% of customers were not satisfied
Ratings & Reviews
Jenny N.
5/29/2024
To be honest we have asked our manufacturers this question before however we have not gotten a definitive answer. We do know that it does not effect the performance.
Brady
12/24/2025
Still working perfect. Has been several miles zero issues
Lazer S.
12/24/2025
Richard K.
4/30/2018
I could not be more pleased with my kingpin adapter. It exceeds all my expectations and makes the conversion a simple process. My brother and me farm together and he is very impressed with the adapter. Others I have shown it to agree. I keep your site bookmarked for future reference.
Jacob
3/30/2021
The product is holding up well and works great. It is very convenient being able to switch from my camper to my gooseneck without having the change the hitch out!
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Kevin F.
1/20/2026
This piece is extremely sturdy and strong. I’ve put 3 electric hummers on my trailer and this piece along with my axles of the trailer support the weight well.