I assume you have the cast iron hub with the bearing pressed on in your 89, and the bearing you got was the one piece unit bearing with the trans? If so, you can use either one, you just need to match the right clip(s) to the bearing used.
The cast iron hub with the press on bearing (older style up to 89) uses two clips, one on top one on the bottom. The one piece unit bearing (newer style 90+) uses one wire clip. They should be 100% interchangeable as long as you have the right clips for either style.
If you look at them side by side the dimensions work out to the same regardless of the bearing style used. For instance, there are even two brands of the one piece unit bearing that are built completely different, but the mounting tab height to engagement surface height works out to the exact same.
In conclusion, 81-95 4 or 6 cylinders can basically use the same bearing, either the hub with pressed bearing or the unit bearing - whichever one you want/have the right parts for.
Also, FWIW, some clutch kits come with the one piece bearing, and some come with the pressed on bearing. When I did the clutch in my girlfriends 87 we found when we took it apart that it had the one piece bearing in it, but we had bought the pressed on bearing. Since whoever did the clutch last time presumably tossed the hub, I had nothing to press the new bearing onto. A quick exchange for the later style bearing (looking it up for a 90 4Runner) at the parts store and we were in business. I only mention that because its possible the trans IS the year he said it is, but its possible a clutch kit that was put in the truck at one point had the newer style bearing with it.
~T.J.
