Also wanted to mention that the 45RFE is the exact same transmission. Soldierguy, you could have the 545 in your Dakota simply by getting a trans controller from a truck with the 545 in it. Ive been told that you can reprogram the existing controller to give the vehicle the 5th gear. Also the 545 will soon have a flash to make it a 645. The trans is basically able to produce 6 forward and two reverse gears (different models will utilize one of the two reverse gear ratios).
Also I wanted to mention that the Hemi in the LX cars (300C, Magnum and Charger) use the 545RFE trans. The 3.5L uses the NAG (MB trans). This trans does not have the torque capacity to handle the Hemi....looks like we have one step up on the Germans!