I wonder what the three threaded holes in the block at the rear of the generator are for?
On some car, not truck applications, those holes were used to attach motor mounts, with a third mount on the back of the transmission. Pickups and bigger trucks used mounts near the front crankshaft pulley and the bellhousing, with the transmission unsupported at the rear. On your truck, the holes have no purpose, since the engine has mounts front and rear.
Jerry
