The early carriers, pre 1962 had a different casting numbers on them but the specs. on the pinion races are the same as the 741 and maybe the bigger 742 cases is what I have heard on here, maybe not as I have not had hands on experience with none of them confused
The 2.76 up too the 6.17 gear ratio will fit in the carrier there made for up

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)