Iam looking for 5.12 complete front and rear thirds to buy or trade for my 4.62 from my 96 x90 with 90k miles.

Is there a part number I can reference?
I'm parting a '91 2 door 5 speed. Isn't 5:12 pretty much the stock ratio for that application?

Yes

Don't forget:  '92 - no ABS, '97 YES ABS...

You may be forcd to use everything in the '97 Rear Diferential and swap the Ring and pinion while the Front Differential may be plug-n-play (unless they changed the sidegear spline count).

Any comments on this?

In that case... I just picked up a 97 Sidekick Sport 8 valve 5 speed 4 x 4  that suffered  transmission failure. In the process of trying to fix it they messed up the interior pretty bad. I have no idea how or why they got so much grease on the headliner...well...I think it's grease...anyway  I'm on the fence about trying to clean it up, fix it up and put it back on the road or part it.
So,  I might have later model thirds if that's what you'd need.
Peter

When you figure it let me how much.

I'll need a few days. I need to verify that the engine is good

Just pulled the rear third from the '91 Tracker. It has a speed sensor. Not sure if that makes a difference or not but there it is. :-)

You wouldn't want mine, because they're 5.83 instead of 5.12, and have ARB Air Lockers on 'em.