Why do some old tractors etc have positive ground are the starters and generators "wound differently," I have no clue and always wondered why?

I have a problem that may be related.

I have a 1937 3/4 ton IHC pickup and the starter went bad, the armature? winding broke in one place.
Might this have been caused by my hooking the positive cable and post to the starter and the ground post and cable to the frame when I should have been reversing the set-up as if it were a positive ground.
I haven't been able to find a local shop that can fix my starter in 2yrs (no title etc) and I've found two identical locked up starters and maybe I can make one good one?

Thanks.