I have done EXHAUSTIVE research on the trans temp add. NBS trucks through mid 04 appear to work by just adding the stepper motor (and obviously the face and needle). Halfway through 04, they start requiring the gauge to be "turned on " in the cluster program. Multiple shops /services can preform this, but everybody is very tight lipped about how it's done. At first I thought maybe a tech 2 could do it, but now I don't think it can. I have one guy near me that says if I bring him the cluster with the gauge added, he can 'turn it on with his factory scanner' I'm not so sure. I recently found one more gauge cluster guy /shop not too far away who advertises the service. I have yet to call on that one.