The Nissan Path

I bought a '98 Pathfinder LE back in February for my son's first car. Done a full tune up, fuel pump and filter, front struts and lower ball joints, new exhaust, and now front and rear brakes and brake cylinder on drivers rear.
The drivers rear tire wobbles when you drive it. Had the tire checked and rebalanced and checked good. Rear brake shoes were worn funny. Shoes were good on top side and completely worn to nothing on bottoms. Shop said wheel cylinder was shot. Had tires rotated and wobble stayed on drivers rear. Took it to get the wheel bearing replaced at Jensen Tire and they couldn't replace it. Said you need a special tool from Nissan. They tightened the bearing up though. Said is was 1/2 turn loose. Wobble is better but still there. Seal looks to have been leaking for a while and said there was a small groove in the shaft from a rock or something getting in there causing the seal to leak. They suggested maybe axle shaft was bent and to get a used one. Can't really find much info on the axle shaft and Haynes manual has no info on it at all.

Nissan does have a special tool that makes bearing replacement a lot easier, but it can be done with a press. Since it is a pressed bearing, I'm not sure how they could have "tightened it up" or how it could be "1/2 turn loose." It sounds like you need a better shop to work on your truck! If there is play in the bearing, it can cause wheel wobble as well as cause a leak at the seal. Could the axle shaft be bent? Perhaps... It's not a common problem and even if you were to get a replacement axle, you would still need to press on a new bearing. This is if you went with a new axle; if you went with used, would you really want to install the shaft with the old seal and bearing? Probably not... So, you're still in the same situation where you would need to find some place to replace the bearing. Most independent shops should be able to take care of this for you and if they can't R&R the bearing, a local machine shop could do the job. Perhaps you'd be better off getting a second shop's opinion?
If you are looking for R&R info, you could try the free "repair guides" section at Autozone.com. You might also be able to download a service manual in the "knowledge base" section at NissanHelp.com or at Nico's website.