I have no hands on experience with these transmissions other than research on the 545RFE, 65RFE, 66RFE, and the 68RFE. That said and on top of what snrusnak said the 545 and the 65 are the exact same transmissions but with different programing in the TCM. Which btw is located in the PCM (not a stand alone) and has nothing to do with the configuration of either transmission. So to my understanding, you couldn't tell any difference between the two just by looking at them. The only different or new transmission worthy of being considered different is the 66RFE which resembles the 545RFE (uses the same housing) but utilizes some of the beefy 68RFE internals producing more torque/strength and better gear ratios. As much as I hate to say it, Chrysler is MISSLEADING the public with the notion that this (65RFE) is a different and improved transmission over the 545RFE....they are flat out lying! Chrysler has LONG aknowleged over and over that they are well aware of the overall poor performance and most important...poor consumer satisfaction of these transmissions. I'm saying that they are well aware of the hp sucking performance of the gear ratios. There's nothing wrong with quality or in other words they are no worse than any other trans put up against a 400 hp engine. It's just that the gear ratios flat out suck, they rob hp from your engine when compared to the competition. They know it, and they know the cosumers know it. What they need to do is abolish the 545/65RFE in Hemi trucks all together and use the 66RFE and the new eight speed as an option. The gear ratios in the 66RFE are much closer together and it has a 3.23 first gear as compared to a 2.97 in the 545/65RFE and it would help improve fuel milage as well. And to the OP, I wouldn't even use the second gear in this 65fFE to race...I'd skip it. If I manually use it in my 545 it would just slow me down or lower my ET, none the less good luck.