01 up uses different neutral and backup lights switch, can convert one way but not the other between 00-down/01 up.
I just got done putting my fresh trans in my 01 yesterday, haven't put fluid in yet...I rebuilt it myself, been done with the rebuild since early last summer, but since it is now a spare vehicle and life has interfered alot since I finished the overhaul, it had sat. Mom died, working on her house getting ready to sell, having to do all the handyman work at mother in laws house, besides, and then it got cold. When it went out I went and bought an 03 for my wife to drive. We both like the 01 better with the 360vs the 03 and it's 4.7, but we've survived with it.we miss the better seats and overhead console among other things, plus the 03 just seems more tinny...
But the 01 also has 314k miles while the 03 only has 142k....
