Hi, just a quick thought, the mk3 timing gear and its relative pinion down are slimmer than the previous model's one ........as the crankshaft is wider (by 3mm if i am right) thus the cases should be wider , hence the pinion slimmer, so if you fit them to a pre mk3 cases, they won't be in line with the cam sprocket.....! but may be it's not your problem?