A standard tranny may take a while to find, but they are out there. I would expand the search to include 99's, they get the same upgraded interior and front bumper, basically the same truck as a 2000. And while the standard tire on the SR5 was the 225/75 many have the upgraded package w/ the 265/70 and it will not cause your u-joints to wear prematurely. Most important thing with tires is the gear ratio, most w/ large tires came w/ 3.90-4.30, some 4 cylinders got 4.56. Do a search for axle codes and when you find a truck make sure it has low enough gearing for the equipment, if it has anything higher than 3.90's then it might be a bit doggy with the 265 tires.