Just from talking to Mopar transmission guys. The NAG1 doesn't have input or output sensors, so it gets it's MPH readings from the brakes. They supposedly take the readings from the antilock brake sensors, average the 4 readings and that is what tells the computer...to tell the tranny when to shift. If you have the antilock parts,check on this before you rule out using them. You've done a lot of nice work installing the LX dash, so if I was doing the same...I would use every inch of wiring from the Charger if you have it. The antilock brakes can be a PITA, but they can be a good thing too.