There were 3 versions of Door Panels used on the 1973-1987(91) trucks:
The 73-76 door panels can only be used on 73-76 doors unless you don't mind drilling new holes and filling in all the old holes.
The biggest being the large 2 at the bottom where the power motor bolts down (see link:
http://forum.73-87chevytrucks.com/smforum/index.php/topic,14625)
![](http://www.73-87chevytrucks.com/techinfo/Doors/73-76panel.jpg)
77-80 and 81-87(91) panels “can” be used on any doors, but require the correct regulator (77-87(91)) the correct specific door handle (77-80 or 81-91)and new holes would need to be drilled.
Pics coming.