I remember seeing this discussed before on a different forum. As I recall the 80-86 doors will work on 87-96 trucks, but not the other way around. Something with the contour around the lower rear corner. I'm not sure how well they fit, but they are supposed to work.
Edit: found it...
http://www.garysgaragemahal.com/#nabble-td27026
It looks like the area around the cab corner is different on the 80-86 trucks. 87+ have the seat belt retractor in that area so they redesigned the cab corner to fit.
I do know the vent window is different on 92+ trucks, the front corner is squared off for dash clearance.[/QUOTE
Would there be any issues with the doors matching the body lines, or just inside of the door is different?
Rock