On my '54 3600 i swapped the rear axle for a Dana 60 out of a 1971 Chevy C-20.
The Dana 60 was only an inch or so wider than the stock Eaton and the only other modification needed was to move the spring perches over some.
The swap let me keep the 8 lugs, a 3/4 ton axle, modernize my rear brakes and get a better rear gear ration (4.10 now).
From what ive read the GM 14 bolt is pretty much just as easy a swap, I just had the Dana available at the time.
Chooglin
