Do Not Use These Adapters
I had one of these for years and thought it was great. Then the adapter tore out my kingpin, the trailer tore off my tailgate and skid 60 feet down the highway. Luckily I had just started out from a red light. If I had been at highway speed, the rig would have rolled.
These adapters put too much pressure on the kingpin. The pin is for rotation only, the weight of the rig must rest on the plate where it contacts the fifth wheel hitch. Searches on the net show many failures like this.
Needless to say, Progressive Insurance is questioning my claim on this hitch setup!
Do not buy the adapter or Progressive Insurance!