The original GMC V6 starter works OK for the 478 but cranks over a bit slow. As far as I know the 305/351 V6 always used a standard or low torque starter.
I managed to score a Chevy high torque starter for cheap and was wanting to swap the high torque housing and rotor over and use the GMC V6 nose, resulting in a high torque starter for the V6.
But I ran into a problem. These is a difference in shaft length. This means I'd have to shorten the shaft and cut a new groove for the metal clip, which is doable.
Another thing I'm wondering about is the length or the starter gear. As the GMC nose is much shorter, these is a lot less travel for the starter gear to engage, provided you're using the longer gear.
As you can see the gear that came off of the GMC starter is a lot shorter. Is this original? In the rebuild kits you always get a longer gear, and the Chevy starter is longer so you have plenty of linear travel. The longer gear in the GMC starter makes the gear almost contact the flywheel in its resting position, which is not ideal.
I can shorten the gear too, I'm just curious why the lengths of the shaft and the gear are not the same and if anybody else ran into these problems when they rebuilt their V6 starter.