63 Dart What Rear end

My 63 Valiant had a 7 1/4 3.23 rear with a 170'' engine.Width should be the same as a 72. I installed one from a 74 Dart with 2.76 for better highway crusin'. The 74 was 1''-1 1/2'' less in width(not sure actual mesurement) and was big bolt pattern. Lets hope you can score a 8 3/4 though I'm sure they were not factory in 63.