[rotorwrench]

There were a number of different versions of the Universal Carrier. The initial versions were in the 21 stud era with 221 cid. The versions most produced during the war used the Canadian C81A type engine to begin with but even they evolved during the war. The Ford Dearborn T-16 version used the 29A 239 cid engine.

I would look for a 59 series engine or maybe a French SUMB engine since they don't need adapters to fit drive train and there are still many of them out there. If you can find an old 29A engine or a prewar 221 engine then it would be more correct but at this point in time, it wouldn't make that much difference and most folks wouldn't know one way or the other. The 8BA would require an truck or Mercury adapter and likely a change of frontal accessories to make it fit and function as the earlier design.