It also dropped my freeway RPMs almost by 300 at 75MPH. What I have found is the torque converter doesn't come out of lockup as soon or as easy as it does with the Dodge TCM. The upgrade only: adds another overdrive ratio, changes the 4th gear shift point, and changes the torque converter lockup speed. The TCM swap won't work because the Jeep TCM uses the PCI bus while the 2000 Durango uses the CCD bus. Pretty simple.Ĭheck out this thread - It has all the info you would need. I 'upgraded' the tranny by changing the programming.