76 to 77, - some differences. Especially 76 to 78. Door panels, ignition, fuel injection plubming (some), emission control valves, vacuum tubing/routing, fusible links, spare tire, rear interior deck/carpet, tail lights, wiring harness, starter, distributor, bumpers, exhaust manifold (emisions), A/C plumbing (some), transmission (if 4 to 5 speed), alternator/voltage regulator, fuse box, seats (cosmetic), center console (cosmetic), dash panel, fuel light, floor temp sensor (if california car),block (swappable), head (swappable if keep manifolds), fuel injection relays, relay wiring, just off the top of my head.
However, - many major parts are interchangeable or identical if usable.
I have a 76 parts car if you need some particular parts, email me.