Thanks very much guys. I have been too busy the last couple of days to make any progress but I may get something done soon.
Nate, I think it is fairly common with these big trucks. This way any truck with a bunk could tow it instead of needing a specific truck. On the other hand trucks that had preloader log trailers had a fifth wheel so they would that style.
Here's a couple pics of the bunk style hitches. The one trailer doesn't even have a pivot
... It must hammer around pretty good on the bunk.
Reg