Original External Voltage Regulators

[68 C10 Driver]

So I want to keep the external voltage regulator, I think it just adds something to the nostalgia of the periods technology. But my question is, my truck has a United Technologies RAB 12A12M on it now...will a RAB 12A12 work? Looking at them underneath both seem to be constructed the same.

I am trying to build up my stock of voltage regulators for the future. I know they make a virtual voltage regulator, but with those made in China so naturally I am concerned with quality...besides I want to keep the C10 as much American made as possible.