Originally Posted by phobos512
Um, the main benefit you get from an 8-speed is that the gear ratios are more closely spaced which allows the engine to stay in its powerband. It being lighter is not the primary reason. All things being equal (i.e. manufacturing techniques and materials) a transmission with more gears ought to be heavier. Obviously not the case here but the 8-speed being lighter is not the main reason you'd want it...
Maybe I should be more clear: the reason the tow ratings improved slightly between 2012 and 2013 is because the 8 speed is lighter than the old 6 speed. All things are not equal and how much the 6 speed should weigh are irrelevant because they are not similar in manufacturing techniques or materials. the 8 speed is lighter, the 6 speed is heavier, that's all that matters. The fact that you have more favorable ratios with the 8 speed had no impact on tow ratings for the 8 speed in 2013.
The final drive ratios are 0.67 for both transmissions in their highest respective gears. The transmission is not the limiting factor behind the tow ratings, the differential is. Yes you have a much lower first gear with the 8 speed (actually the first 2 gears), but the differential is under the same amount of stress it would be if the truck had the 6 speed because the speed of the output shaft and therefore input pinion will be the same at the same speeds. The only difference is that the transmission will be in a different gear.
I love my 8 speed, the added gears have improved power availability substantially but do not allow it to tow more than it could if it had the 6 speed, the weight savings does. There are other threads on this topic as well.