On my car, I swapped in (From stock 1985 SE) a 1986-88 rear quarter and decklid- there was really nothing difficult or "Special" that had to be done.
I did not include the ground effects, nor the GT rear facia (I like the bumper-pad rear)
I did not like either the bumper-pad (Stock) front facia nor the GT facia- went with the 87-88 base car nose. On that I had to also swap in the bumper egg-crate (behind the facia)
When I pulled the GT quarter panel off the car in the JY, one window was already crazed and the other broke due to ME not being careful with that stud under there...SO I created the custom "B" pillar covers out of aluminum.
Also, the Later nose has a rounded rub-strip while the rear facia has the ribbed; Have actually not done anything yet but plan on replacing all of the side (Ribbed) with the later rounded.....And I know someone who is 3D printing pieces that can be glued into the rear so it comes out (Matching) rounded.
[This message has been edited by cvxjet (edited 01-30-2022).]