I have a 6 volt generator on the bench with part #OHA-10139-A. Does anyone know what year/engine this generator is intended for?

My 54 F100 had a conversion to 12 Volt when I bought it, and I'm going back to 100% stock. Its been a little challenging to find all the original brackets. Truthfully, I don't recall where/when I picked up this OHA generator.

Ultimately, I'm looking for a FBB-10002-A 50 amp, But I'd take a FBC-10002-A 35 amp if anyone knows where I can purchase one.

 

Any information would be helpful - Let me know what you know.

 

If an eBay ad is to be believed, 1951-1955. Item # 142508289073.