I am looking for a 88T, 440mm 15mm belt. I have looked at all the suppliers I can find but only run across 425mm or 450mm belts. The problem being 425mm is barely to small and 450mm is barely to large. The only belts that will work are a 86, 87, or 88 Tooth.
I got mine from here
You can customise lengths if this helps
Unfortunately, they jump from 425 to 450 as well.
I can find almost any belt from vbeltsupply.