Had enough of my wobbly steering today, and after doing a bit of research, I called Safari LTD. Forget the gentleman I spoke to this morning (I'm sure if I ask, they'll tell me).
In any event, I asked them some generalized questions. They gave me a basic rundown of information on steering racks in general. It seems that most of the newer vehicles have a rack (or gearbox) that's in front of the wheels; doing so allows the wheels to 'pull' at the rack or gearbox, and causes things to wear down much more slowly. However, the 3rd Gen 4Runners have a steering rack that's behind the wheels, meaning it has to 'push' the wheels, which means it'll wear down more quickly.
It's not just the 3rd Gen 4Runners, of course - it's any steering rack or gearbox that's behind the wheels. As far as upgrades, they don't give EXACT specifics beyond the fact that the internals are upgraded, OEM specs are exceeded, etc. (though if you call any company they're not going to tell you each and every , though they did mention that their steering racks are manufactured by a company called Atlantic Engineering, Inc., I believe it was. The $495 for their steering rack includes the ITRE's.
In any event, I do know the total for me was right around $540 (including shipping). For those who have to replace steering racks and DON'T have poly bushings, they have 'em and will sell them to you for $24.95.
It will be here Thursday and I'll have it installed and take pics and all of that once done.