Originally Posted by tw1st3d5
The upgraded alt has a 7 groove pulley and is just a hair larger. I measured it when I swapped mine and it was something like .07" larger. The 6 grooves closest to the alt line up perfectly with the normal belt alignment on the 4.0. In my opinion it wasn't worth it to swap the pulleys.
no chance of the belt walking over a groove(stupid ? i know lol)