With the exception of the shallower axle seal bore, '62-'64 housing ends are the same as the newer version. In other words, you must run a narrower wheel bearing lock ring to clear the inner seal.

Correct housing widths are listed in Moparts Tech Archives as well as Hollander's Interchange.

B-body housing widths (end to end):
'62-'63= 53 1/4" (And '64 Max Wedge)
'64 = 55 5/8" (Exc. Max Wedge)
'65-'67= 54 1/4"
'68-'70= 54 15/16"

All these housings share the same perch dimensions (44" on center, pinion 4 degrees up when perches are level).