The amount of cars still on the road today, that require matched belts, have decreased considerably. With this taken into account, there is less demand for matched sets of belts which translates to parts stock which has low to no turnover which can mean no more matched sets. Parts being stocked are like having employees. If the employee makes you money you keep them around, if they don't make you money they get booted.Unless you are talking about certain federal employees then its the other way around. There may be some companies around that have matched sets, you will just need to hunt them down. Gates had a coding system which if you could decipher it would let you know if the belts were from the same run/drum so you could get a matched set without having them taped together. I've been away from them for too long so I don't remember how to decipher the code. Also its beneficial to make sure all the accessories line up in the same plane when running v-belts. If you look at them from the side, you will see that various units are skewed which contributes to belt squeal, belts being tossed etc.