I have used both vbeltsforless and vbeltsupply. Both are good - I usually prefer vbeltsupply for no particular reason.
I used to really like Jack's, but on a recent batch of orders I got 3 WRONG parts, and their advertised "service after the sale" was very difficult to get. Plan to be on hold for a while. In fairness, the bad parts were (I believe) due to MTD/TroyBilt/Poulan/Weedwacker having faulty part numbers on the parts diagrams. In one case, the parts was simply manufactured wrong by Poulan.
I used to really like Jack's, but on a recent batch of orders I got 3 WRONG parts, and their advertised "service after the sale" was very difficult to get. Plan to be on hold for a while. In fairness, the bad parts were (I believe) due to MTD/TroyBilt/Poulan/Weedwacker having faulty part numbers on the parts diagrams. In one case, the parts was simply manufactured wrong by Poulan.