One major difference is up until 2003 ABS was still optional, so in 02 you had a choice. 03 they took the Ebrake assembly and rotated it from the top of the rear axle with the cable routed over the leaf springs to the bottom of the axle with the cable routed under the leaf springs which makes it easily destroyed by rocks or timber. That's the only differences I've noticed off the top of my head. Remember that they also had a manual T-case, no push button on the stick ,just 2hi, N, 4hi, 4lo and manual hubs option available at the time also, I replaced my elec. T-case with a factory manual T-case. Remember to inquire about all recalls and make sure they have replaced the upper ball joints if the vehicle was part of that era. The manual T-case and hubs was only available in the ext. and single cab models. I read right past the fact that you are looking at double cabs, sorry.