For the most part.. Different PCMs but motor is the same as well as all the suspension and such (in which case, everything up until 03) Trans is a bit different though. believe 97 still used the 4T60-HD while 98 and up they used a 4T65-HD.. Also, while on the subject of transmissions, up until 02 the trans is interchangeable. After 03 they started changing valvebodies and oil pumps so they won't work on older GP's