I'm just trying to envision all this in my mind as I'm sure a few others may be too.When the alternator base plate is removed and the oil has been drained leaving the drain plug out, you have the Lewis pin aka pin that holds the split gears aligned, on a cable that you can run through the drain hole out the hole in the back of the motor and to the alternator drive gear in your hand. Insert base plate gear assembly, pull wire and Lewis pin out of drain hole.
So this lewis pin sounds like it is a pin that is inserted in an alignment hole found in both of the split gears while the alternator drive is installed?
Yup?
Nope?

