Pulled this one out from behind a barn a couple ago,was last inspected in '84. 71 Twister /6 3-speed disc-brakes,8 3/4 3.23 sure-grip i have no idea why a /6 would need an 8 3/4 rear!
Few years back I picked up a 71 Valiant 4 door slant 6, 904, HD cooling system, disc brakes and 8 & 3/4 with 3.23s in it. Why equipped that way? Because the old man I got it from did some towing and wanted a heavy duty rear end, discs and cooling for towing and the slant for economy when he wasn't towing.