8.75 rear in 71 swinger slant six car?

One thing that i learned years ago was to never take anything for granted when it comes to options on our Mopar cars.
Keep in mind, the factory would allow an upgrade on a car to keep it going down the assembly line, but not a downgrade.
There was a lot of weird combinations that make little sense other than someone special ordered it, or on the assembly line, that's all that was available at the time when the car was being built.
I always never take anything for granted, always look at the car closely!
Also, these cars are getting pretty old now, so anyone could have changed anything years ago and it would look like it was built that way from the factory.
Repair shops were notorious for sourcing parts from junk yards and they didn't care if it was original, just as long as it fit and they got paid for the job.