Originally Posted by country-boy
I'll take a shot, but this this is just a guess.
The 8HP70 has a very low first gear, around 4.7:1. They probably figure with this kind of torque, they can get away with the 3.21, and keep the mpg higher.
They still offer the 3.92 for the guys that want/need the higher towing capacity.
Again - based on nothing solid. If someone has better info, great!
I would venture what you are suggesting might be part of the reason.
With the 8 speed auto and the 3.21 gears, the Ram truck actually accelerates faster than the 6 speed auto with the 3.55 gears.
So for Chrysler, the "base" or "tallest" gears (3.21's) now offer better acceleration and better gas mileage than the outgoing 6 speed with 3.55's
But the doesn't explain the reasoning to eliminate a perfectly good option.
See for me, the old 6 speed auto and 3.55 gears truck accelerated decently, but not great. The 8 speed auto with 3.21 gears is a fraction better, but not enough.
The 8 speed auto with the 3.92 accelerates great, but also gets the worst gas mileage.
So the best option is right down the middle, the 8 speed auto with the 3.55 gears. You get noticeably better acceleration than the 6 speed auto with 3.55 gears (actually, the 8 speed auto with 3.55 gears probably accelerates faster than the 6 speed auto with 3.92 gears), plus you get better gas mileage with the 8 speed 3.55's than you do with either the 6 speed auto with 3.55's or 3.92's or the 8 speed auto with 3.92's.
So that's the reason I got my 2013 Laramie with the 3.55's, it's the best combo of all gear options.
And since I won't be towing anything even moderately heavy (over 5000 lbs), nor do I live at higher altitudes or the need to pull up steep mountain grades, the 3.92's are not really needed for me.
I guess if I had to choose, which it looks like I'm going to have to when Chrysler swaps out my 2013 for a 2014, I'll go with the 3.92's.
My guess it was a manufacturing cost cutting option for Chrysler.
Not having to offer 3 axle ratios on many of the trucks is probably saving them money, since the $50 option price for the 3.55's or 3.92's, clearly isn't a money making price. But I'd of just preferred them to raise the option price of the 3.55's and/or 3.92's to like $150 then, and keep the 3 axle ratio options available.