Hello names Nick, quick question I have a 2002 Dodge Ram new body with the 45RFE trans I have a used 04 545RFE trans from a 1500 Dodge Ram, would it be Compatible/work with the 02 ram. If any one has any info please let me know thanks.

 

Same transmission. The number of gears (and hence the designation) are due to programming differences. In your 02 the gear list is 1, 2, 2P, 3, 4 (OD). You can actually take a TCM from a Jeep (2002 Jeep TCM controller, P/N 56041905AD is the one that has been proven to work) and plug it in, get a quick learn and you will gain the extra overdrive gear (the only difference). Then your gear list will be 1, 2, 2P, 3, 4 (OD), 5 (OD). There is a pretty extensive write up that I can't link you to on this site (it's on another).