Like stated above, the pos. neg. ground makes no difference on the starter rotation. Looks like the Chevy and GMC truck starters from the 40s up until the 1st production 55s were pretty much the same. I know from experience that the shift lever that throws the drive in was different on the GMC and because of this it made the drive end housing different.....they were interchangeable but different....have yet to figure that one out. After 55 GMC went to more "odd ball" starters with different housings, starter drives etc. Using Buick motors in the GMCs made them that much more different...along with motors such as a 270, 302, 316 etc..Most all of them called for different housings, drives etc.
Ken
