To answer your questions -- I have four (4) new sets of Yukon Gear TRX250R transmission gears (5 pieces) that fit 1988/89 trans in new packaging. These do NOT include all the transmission gears, only the ones for which the stock Honda gears are not strong enough to withstand high hp. Two of the five gears in each set are made from 9310 and the other three are made from 4320. I originally had 500 sets made by US Gear in Chicago when I owned Randy's Worldwide Auto Parts and Yukon Gear & Axle. These are from my private stash and available for sale. I also have a set of Yukon Gears for the first year Yamaha 660 Raptor in new packaging and for sale. the Raptor gears are not only stronger, they also help shifts and have back-cut dogs which keep them from jumping out of gear. The TRX gears are not back cut, but MUCH stronger than the stock Honda gears. They will fit the 1986/87 transmissions IF the right other parts are updated. I don't recall which other parts need to be changed in order to fit the early TRX transmissions, but I used them in my 1986.
