When I get around to replacing it, I'll pop the spring out of the old one, and see if I can shorten it. If I booger it up, no loss. Joseph
Your tech is good -- actually I don't think there is any other way to do it. The existing yoke seal can be pried out, and a new one hammered in as described above. This is a handy moment to replace the two u-joints, they're cheap also. Hint, use a large C-clamp to remove and then replace the pieces. This is also a good time to check for wear at the sliding part of the driveshaft -- try it with no seal in place, shake it around. Any movement means you also need to replace the bushing.
OK ! I might have learned something. Got an axel seal on an International Harvester that leaks when tilted going thru ditches. Going to put the evil eye on the old and new seals now. About that tail shaft seal, any of you ever looked at the condition of the bushing the yoke slides in ? When that bushing wears out the yoke can move more than the seal can compensate for then the seal leaks. On every single one I have had leaking, the bushing was worn. There is a set of tools made to remove the bushing and replace it with a new one. Then your new seal will have a fighting chance of lasting for many years. A new bushing also benefits by getting rid of an annoying vibration you probably can't find the source of. Check with the older parts houses in your area or transmission shops, they may rent or let you borrow the tools needed. Pay attention to that bushing, it will have an oiling hole that has to be aligned properly or you are wasting your time. Mark your drive shaft and rear yoke before you remove it so it can be put back in the same position for balance reasons. Easy job if you have the right tools, takes less than one hour and worth your trouble. Sounds like Burningbush knows about this from experience too.
Shows you how rusty I've become: I completely forgot about the bushing. I need to pay attention to their age.
I figure that I had another week before the whole thing went kablooie on me. Until then, I wondered why my truck went "clunk" when I put it in gear. When I installed the rebuilt engine/tranny, I ... ummm ... replaced the U-joints as well. No more "clunk!" Joseph