Reawakening this again...
Fate has a horrible sense of humor. I pulled one bracket out (without pulling the AC compressor off it... I'm not dumb enough to do that up here in the rust belt, the spindly little bolts always break) and put another in because the original one had horribly bad bearings in the fan pulley mount. Put the new one in, with AC compressor, off a parts vehicle I had.
Fast forward a few weeks to today and it throws the belt. Turns out all four bolts (well, three and a half of them) had broken over the years and a half inch stump of each, packed with rust and aluminum oxide, was all that was holding the compressor in place, so the last bolt finally gave way completely and the compressor leaned forward.
Been trying to get the damned compressor bolts out, have only succeeded in breaking the stubs even shorter.
I did take the compressor off the other bracket though (the one with the bad fan bearing) and the four bolts came out without a single hitch. That has never happened to me. Sure enough, it's a full moon tonight (not kidding.)
So now I have a bracket off a 94 with a good bearing in it, and 4 solidly corroded in place AC compressor bolt stubs.
And another bracket off a 91 with a bad bearing in it, and 4 perfectly clean threaded holes for mounting the AC compressor.
I guess I'll find out if I can get the bearings out of the 94 bracket without destroying them, and the bearings out of the 91 bracket without destroying it. Time to find the gear puller and the mini arbor press...
EDIT: the mini arbor press didn't quite fit the bracket assembly, and I got frustrated. So the solution involved a gear puller to get the flange off, then a BFH to "press" the bearing out, BFH to "press" the bearing back in, and liberal oxy/ace application to make the flange expand enough to drop onto the shaft. Then I sprayed the damn thing with the garden hose till it shrank into place.
It didn't quite shrink true (so there is a fairly small amount of wobble in the pulley and fan now) and I'm sure I greatly reduced the bearing life, but I'll be able to drive it tomorrow. Ordering a new bearing assembly now, hopefully it'll arrive before the one I "pressed" out of the donor bracket and into the recipient bracket (with my BFH) blows up completely.
EDIT2: on my 91 bracket and 94 bracket (and probably later as well) it is a single-unit bearing and shaft, instead of the two bearing units that are apparently in the RENIX brackets, per post 32. Trying to find the later style bearing/shaft assembly now, using the part number Matthew Currie gave.