I started looking at the tailgate. I have one from 87-70 era truck, but looking at it, the diameter of the hinges are different. Went out and got the newer HW on the bed side (hinges, bumper stop, cable and latch bolts). I was thinking it was going to be bolt up, but looking at it more carefully, looks like they are drilled differently, and the 86 is shaped differently around where the latch bolt will be installed. The good news is that the brown truck in the photo above is actually a newer style bed while the white one is old style. So I've got a reference. I'll take some pictures that show the issue and the conversion - in case anyone is in same boat. If there is a good write up on this, I'd be interested, but haven't found it yet. There was one that was pretty good, but no pictures.