Since this is a fairly commonly asked topic I figured it was time to sticky info about belt sizes and availability. I will keep adding info as I find it or as people send it to me.

You can search for sizes here

Product Catalog

Here is a complete Gates belt Part # listing along with sizes. This link does not have every size, seems to be more common ones.

http://www.gates.com/oreilly/PDFs/SizeListings.pdf

Lots of good cross reference here, as well as size look up.

Access Dayco

Goodyear Belt Info

Gatorback® Poly-V Serpentine Belts | Goodyear® Engineered Products

 

So I extracted some pages from the Gates master catalog to find the belts that may be useful for us. I did this mainly for supercharged setups, but you could look up any belt as long as you know the width. I divided it into 2 files, one with normal belts, and the second one with HD belts. There is not as large of a selection with the HD belts though, so you may have to settle with a normal one.

I extracted the 6rib through 14rib belts. They have the most by far of 6 and 8 rib belts.

The 3rd digit (2nd number) is the number of ribs, ie. K08xxxxxx is an 8 rib belt. They are sorted by part number in the first part and then by length at the end.