Technical Pos ground to neg ground

About the heater fan motor:

In my 1952 Mercury, I bought a fan motor for a 1965 Ford Mustang. It looks identical, but the shaft is thicker, so I put the hamster wheel in a lathe and carefully drilled the centre hole to the right dimention. (I guess you could get the new motor fastened in a vice, connect it to a battery and use a file to make the shaft thinner until the hamster wheel fits?

Rune Waltoft from Norway