1971 Demon fiberglass fender extensions

i couldn’t care less about them being “correct” I have them because they’re significantly lighter than the pot metal ones. I just need to determine which studs fit
My 71 Demon has the fiberglass extensions on the front. I was lucky enough to find a nice pair with the chrome trim in nice condition but they are the pot metal ones. I think the base 318 cars got fiberglass and the 340 cars got the pot metal extensions. The car I got these off of was a 340 car.