I bought a set of 'gates' 2wd alternator belts off eBay the other week and have just gone to fit them and discovered they are different lengths to each other. Surely they should be the same as each other? They both have the code 6272mc marked on them but one has 0.A marked on it and I've counted 121 teeth on it and the other has 0.B marked on it and has 122 teeth. Anyone know which is correct and which is wrong?