So I've got this '49 half tonne I bought last year, and I have yet to turn it over. I had previous starter troubles, and now I've gotten another. I've tested this starter on the bench, and when I have it on the bench, it'll turn and spin really nice when I jumper a battery to it.

This is the puzzler though; once I bolt it into the truck, it shorts. Doesn't even turn a little bit. I'm not using the truck wiring, this is just with a pair of jumper cables, one to the terminal, one to ground it. I've tried it so many times now. Shorts everytime.

Is there something I'm missing here? I appreciate your advice and insight as always.

Matt