They changed the shafts in '72? I have a '75 closed knuckle highboy (had divorced 205 and 390/C6 which went to another project. The frame will become a trailer soon unless someone needs one, but it's in Seattle) I'm using my old front hubs (5 lug) on the D60 housing to make it a trailer. (shame cuz it's 3.73 posi)