Aside from a few unique yearly changes the GP's shared the same body style for 73 through 77 model years..
They share lots of parts w/ other 73-77 GM A-Body cars...Chevy Chevelles & Monte Carlos, Pontiac Lemans, Olds Cutlass and Buick Regals etc..
A lot of the GM product shipped into SA came from Canada and that's always a great thing as you can document your VIN through GM Canada for cheap..
Here's the link to their service w/ contact #'s...ask for George and tell him Pete sent you!.
http://www.gm.ca/gm/english/shopping/parts/vintage