Tractor has to be split to gain access. When leaving the front shaft out, the rear shaft slides forward. On the rear shaft there is a support bearing, with a seal in front of it. The seal rides on a collar. There are actually two collars, one in front of the bearing and one behind. Both of those collars have rubber on their insides. The rubber inner diameter seals the collars and it also kinda helps hold them to the shaft for installation purposes. Without the front shaft in, the rear shaft is free to move-but when it does, the rear seal collar slides back a little and allows oil to leak past. As said, it's not hard to replace the stuff but it's not a walk in the park either, especially for someone who's never done one. About 4 hours for me, my first one was like 4 days.Would love to know if there's a tip to do this on a 30-series. I had the prop shaft slide forward from the clutch housing on me when I had to reposition the tractor and the front driveshaft (under the oil pan) was removed. It felt like it slid forward not quite 1in. I was able to slide it back but now have a pretty hefty hydraulic leak from the split pin in the clutch housing and I can't tell if the 4wd is engaging (didn't want to drive it much with the leak, but it didn't feel like it). If there's any way to fix this without splitting the case I'm all ears. Can a sleeve be slid along the mid-case shaft to possible push an oil seal back? The WSM images aren't the best for visualizing the arrangement in the mid-case.
Do it right or don't do it. You don't want to have to do this job more than once. Replace the shaft, both collars, seal, bearing, spacer, and snap ring. That's the only "right" way to do it; IMO.