Originally Posted by turtle64b

This doesn't necessarily answer your question, but here is the size and part or the larger pulley. I can check when I get home if I have the old one in my parts tub.

From another post:
If you switch to a smaller than stock SC pulley you won't have enough adjustment with the stock idler so you need to go to a 64mm idler pulley to take up the slack (Gates #36225)