i have a 2003 gmc sierra z71 with a 4l60e. i lost 3rd gear. i was told i had to change it out with another 2003 tranny because off changes in the electronics. they have 2 2002 trannys available but said they could not be swapped out with a 2003 model. anyone no if theres anyway i can use the 02 model. how much of a difference would electronic changes make? the trannys looked exactly the same