70 Dart Quarter extension gasket

So the car in my avatar was bought new by my father and I got it from him in 1975. When it came all apart for its first paint job there were no gaskets front or back. In 1983 I bought a 70 Swinger with 27,000 on the clock. In 1998 it came all apart for its first paint job - no gaskets front or back. The 70 GT I'm working on now was wearing its original green paint and again when disassembled no gaskets front or back. I've pulled several other 70 Dart front ends apart for parts and have never seen them.

Maybe it's a 71 thing??