Joe, I wanted to be able to use a modern starter. I wanted to use the late bellhousing attach rather than have to take off the clutch and flywheel every time just to remove the bellhousing. I didn't know I could find a GMC bellhousing w/ the slanted mounting pads. I guess those are the main reasons. I guess we all have to learn this stuff as we go along.
Ed Pruss
Longmont, CO