Hi Dan,
Your second gen 4Runner should have the ADD system, which will NOT require the Warn hub conversion kit. The conversion kit is only required for 4Runners with Automatic locking hubs, such as my 89 was equip with from the factory.
For you - you will have plates that are bolted on where the hub assembly would be that lock the wheels to the axle, essentially deleting the need for a hub in which case the ADD system takes over. You will replace them with your new manual hubs. I am pretty sure you won't even need to take the wheels off the car, nor lift it off the ground. Very easy job.
I have been running Warn manual hubs on my 89 for a year and a half, and they have been trouble free. They are running on my truck which has 31x10.5 tires, that wheels hunting trails regularly and snowy road and trail conditions.
I would hunt down a pair of AISINS first if I could, as suggested...but if you cannot then the warns are great. Mine have been trouble free, reliable, lifetime warranty on them. Turn easy in the cold (if you do not grease them as per install instructions). Bolts have never loosened as some report, I mean, they are just as tight since day one. Not sure how it goes on a monster wheeler with 37" tires - but what doesn't break on those rigs?