Well I have a 02 4wd ford F-150 with a 9.75 rear end in it. Recently the outer pinion bearing went out due to bad axle seals and running low on oil. When inspecting the pinion I found that it had gotten bent, probably when the rear locked up. Well i found a used set on ebay off a 2000 F-150, which should of worked, but I found out different this last weekend. I spent most of the day trying to set up the pinion, but never could get the nut tight enough to get rid of almost a 1/4" of play. So I figured I would compare the two pinions and found that the 2000 pinion's shoulder were the crush sleeve sits is about 1/4" closer to the threads then the one off of the 02. i have called the local ford garage and they know nothing of this, I also searched and found that in 99 Ford decided to change the pinions in the 9.75, but since I have a 2000 and a 2002 it should be good. Hopefully someone can help clear this up for me, and by the way thanks for taking the time to read this.

 

 

Unfortunately for you, they did change the housings. There is a spacer available to make the shorter one fit the newer housing, but you are sol on the longer one. Need another gear set. Also, used gears will most likely make noise if the gear pattern is not exactly as it was in the housing they came out of.