Hi,
I´m currently restoring my 1968 Dodge Dart GT, with a new engine and transmission (273 -> ´71 340 and 904 -> 727), and I am also going to change the original 7 1/4" rear axle to a 8 3/4" from a 1967 Valiant. It had a 273 Commando, and should be the original axle for it as far as I know...