As I understand it, the problem isn't with the gear itself, it's caused by the bushings in the 05/06 OPDA's not getting enough lubrication. That causes the shaft to bind, which causes excessive wear on the gear. When you mentioned "04 and earlier", did you mean just the gear? I think the gear is the same. The 05/06 OPDA's themselves are different and not interchangeable the 04's and earlier.