I had a 71 Challenger that was a loaded 318 car. It had a 7 1/4 rearend in it from the factory. I jerked that thing outta there so fast it would make your head swim....lol. Swapped in an 8 3/4 and a 727 at the same time.
Yeah, that's the weird thing, I've parted a bunch of 318 70-71 E bodies back when they were cheap & most had the 7 1/4 but for some reason the slanty cars seem to get the 8 3/4.....