If you have the rear diff lock there will be a button to the left of your steering wheel that says RR DIFF LOCK, it is just a small button, I beleive it lights up orange. Push that button in 4lo under 5 mph and your two rear tires will be locked at the axle, meaning each will receive 50% of the power to the rear all the time. When open if one side come off the ground it has less resistance and therefore receives all the power, so you will be stuck if one rear and one front are in the air. With the locked rear your other tire will pull you off the rock and you'll keep moving, same theory in front. Toyota never put a front locker on 3rd gens, so if you want one you need aftermarket, but with the IFS and 7.5" ring gear some run into problems on real tough terrain w/ locked fronts, you could get a true trac or something though. Your gear ratio is probably 3.90 or 4.10, 4.10 or 4.30 if you're locked. With gearing the higher the number the lower the ratio, the lowest offered in 3rd gens was 4.56, but those may have only been in 4 cylinders, the V6 low option was probably the 4.30. With 4.10 every time your driveshaft spins 4.10 times your wheels will turn once, so the lower the ratio the more revs the motor has to turn to maintain speed, so your RPM's will be higher with a lower ratio. People gear down to compensate for large tires and put the RPMs back to stock.
