The 4-wheel, 4-channel ABS started in 2001. That means that there's 2 separate brake lines to the rear axle starting in 2001. Based on that, '96-'00 rear axles might be easily swappable.

The 4-wheel ABS started no later than '99 -- possibly earlier. The '99-'00 had 4-wheel, 3-channel ABS (only one brake line to the rear axle).

So do you have just 2-wheel rear ABS or 4-wheel ABS on your '96? Just one brake line to the rear axle, right?

My only concern with saying all '96-'00 rear axles are swappable is that Toyota might have changed/improved not just the ABS computer but also the wheel sensors over the years. I have no idea. It would be best to verify at a dealership's parts department that the replacement ABS parts are the same within the rear axles of those years, then you could feel more confident with model years further from your own.

I'd definitely recommend trying to find some sort of pull-n-save junkyard within a few hundred miles of where you are. You'd be amazed at how much money you can save if you have to remove the part yourself. I've helped friends get complete GM 14-bolt full floater axles for under $100 at those places.

I think it was just a coincidence that the people you talked to hadn't seen problems with the rear axle seals along with the rear locker. I've blown out both of my rear axle seals and I had the stock rear locker with 4.30's.

Also this post in the Toyota forum archives might help a little with gear ratios.