Just mounted a Curt brand frame mount hitch on my 86 M1009 Friday. It went on perfect.

I even left the pintle hitch on, I did have to take the small tube off. I guess it was a brace for the Military hitch. The new hitch went right in and seemed to take that little tube braces place, every thing was real solid. I have already pulled my 20' flat bed trailer with a pretty big load of chain link fence and quick crete.
Next project is get the fuel gauge working,

replace heater core before cold weather- just by passed for now. Using this M1009 as a daily driver and I have been happy with it!!! Oh, one note on installing the hitch. I had to use dental floss to fish the foreward bolts through the frame to their holes but it wasnt to bad.
I did forget this, and another member ask me about it. I did have to take a sledge hammer to the pintle chain hooks and bend them to where they are sraight out, flush with the bottom of the bumper. also I shemed the hitch with washers to level it but it was no big deal to do it all works really well. When I ordered the hitch I just told them it was for a 1986 Blazer.