Andersen Ultimate 5th Wheel Connection Gooseneck Mount.
It came on a camper we bought. In great condition. Sells new for $1000 .

Features from web:
The future of 5th wheel trailer hitches, the Andersen Ultimate 5th Wheel Connection is the lightest and most affordable way to connect your 5th wheel trailer to your short bed or long bed truck. Strong, robust, and simple, the Andersen rail mount design and gooseneck design give you an incredibly smooth and quiet ride, unrivaled by any other 5th wheel hitch on the market today.

The ball of the Ultimate 5th Wheel Connection rides inside a greaseless coupler. This means that unlike other fifth wheel trailer hitches for short bed trucks, the Ultimate Connection eliminates dirty hands and mess. Because the coupler rides on a ball, it has more swivel in every direction than all other 5th wheel hitches available. This also gives you the ability to couple or uncouple your trailer on uneven terrain.

By providing a remote cable attached to the coupler, this hitch eliminates the need to climb into the back of your truck to disconnect the hitch from your 5th wheel trailer. With nearly 3" of adjustable height, the Ultimate 5th Wheel Connection is setting a new bar in the industry.

• Rated at 24,000 lbs. GTWR and 4,500 lbs. tongue weight
• Three height adjustments: 16-1/2" lower position, 17-11/16" middle position, and 18-7/8" upper position (from bed of truck to top of ball mount)
• Keeps your 5th wheel warranty intact
• Works with all standard brands of gooseneck hitches
• Base weighs only 35 lbs.
• New ball-funnel for easy hook-up
• Even works with 3" off-center ball
• Base can be removed or installed in less than a minute by just one person
• Features a patented remote latch/unlatch cable