"But isn't that retainer on the inboard bearing, not the outboard one?"
With 'inboard' bearing do you mean a bearing on the other side of the axle (the inner side), cause there is none: it just 'hangs' on it's splines in the dif's case. I thought the thing Haynes talks about might be a ring that kept the wheel bearing from sliding further onto the half shaft.

There is no special tool for pulling (or pushing actually) the bearing shells into the axle tube. I just gently tap them in with a hammer. Once in place they are a snug fit so there shouldn't be any misallignment possible. (although your previous bearings seemed to be worn unevenly, hmmm...)

I always fit the halfshafts including bearings + shells, and then have a look at the position of that cilinder-thingy and the pinion shaft. I then move the whole axle assembly by tapping on one of the bearing shells (depending which way the assembly has to go).
After the half shafts are both in place, I check to see if both bearing shells are 'home' (no play on bearings).
Start on one side, measure shim thickness, bolt on the shims and backing plate, then again check to see if the bearing shell on other side is still home, check for shim thickness and bolt on the backing plate.
Oh, and dont forget new grease on the bearings.

Hope you and/or the work shop get it sorted.
good luck, cheers ben
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Daily driver: P130, '65, B18+M47. In the proces of restoring: P131, '69, B20+AW71L. (www.knutselsmurf.web1000.com)