Need help with Hitch on Coachman Cadet 1978

We have a 1978 Coachmen Cadet renovated to new condition. I want to replace the tongue/underjaw on the A-Frame hitch which is welded to the frame but cannot find any name on the hitch. On the back of the underjaw is stamped 66-00011.
Can anybody help me with information about the hitches Coachman was using in 1978?