Hey John, been meaning to reply on this one, just haven't had a chance to get a good picture of my hitch to post. [IMG]
http://community.webshots.com/user/Longbox55/trailer hitch[/IMG] The one I have was custom made using an '88 Chevy hitch for the pattern for the side plates. The frame width is 34". We used a 3" square tube for the drawbar and the receiver is a Reece item from a local machine shop.
For a rear bumper you may have some work cut out, it looks like the frame has been bobbed for the dump pivot. It also looks like the pivots were mounted were the bumper mounts would go.
If you are giong to re-install the dump mechanizm, you may have to either make your own bumper mounts or not run a bumper. You may concider having a combination hitch/bumper made at a machine or sheet metal shop. I have seen them on later trucks, they look pretty good on a heavy truck like yours.
You may want to get an assembly manual, they give the dimensions for the frame. That'll help if you have a hitch made and how the bumper mounts.