rear end... pinion seal and bearing

The rear end started leaking, and slowly getting worse. I filled it up, and didn't think much of it until I started getting some nasty growling from it.
I crawled under the car, and noticed I can move the pinion side of the driveshaft very noticibly from side to side. Maybe up to a whole 1/8 of play in it.

My questions: How terrible of a job is it to replace the pinion bearing? Can the pinion bearing be removed and installed without a press (maybe using the wheel bearing tool)? Anyone have experience enough to guess if the gears will need to be replaced? At least that part won't cost to much, since everyone takes stock gears out.

I'm not looking forward to this job. I expect it will be easier just to pull the whole rear end in this case... which makes me want to price a used rear end.

I'm not very interested in adding gears. That adds at least 200$ to the price tag, and I already have a toy... the 88 4cyl turbo. If I have to replace the gears, it will be another set of 3.27's, or 3.23's. whichever was the factory option. They only take me to 35ish in first, which is very reasonable. I just want to know what kind of mess I'm getting into with the pinion bearing. Certainly, I can set up the backlash on the gears.