Thanks for the info. I was using a 5L-440 which is the belt sold here for front mount/alternator. I think I will try both the 42 inch and 43 inch belt. I measured but it could go either way. I'll see which is a better fit and return the other.
I found this handy conversion chart between 5L and B belts. It is exactly as you say - B#+3= outside inches
http://crossbelts.com/kevlar/5lvbeltsizes.html (these are obviously for kevlar belts)
I have read that B and 5L are the same dimensions except that B belts are 7/16" thick and 5L are only 3/8" thick.
So three questions:
1. Should I use 5L or B?
2. Should I go with Kevlar or does it offer no benefit?
2. Cogged or smooth?