@WXman
I forget we're in the ED subforum. I take back what I said about being equal off the line. I was thinking of Hemis.
However, anywhere in between stopped and Interstate speeds, your statement that 3.92 "will accelerate with more ease" is just incorrect. It totally depends on specifics. A speed that has the 3.21-geared tranny in 2nd (or 3rd or 4th, etc.) gear and the sweet spot of RPMs will accelerate better than a 3.92 in 3rd gear at whatever RPM that works out to. Because that's what happens, right? When you're driving along at any of those intermediate speeds, the 2 will either be in the same gear or the 3.92 truck will be in a numerically higher gear. And when you're driving along with a 3.21 in 4th and a 3.92 in 5th, which one is going to accelerate with "more ease"?
Yes, the 3.92 will hold 8th more of the time than a 3.21. Duh. But, it is incorrect to say that that means it will get better mileage all of the time. With the torque curve of the ED, there will be plenty of scenarios where the fuel economy of lower RPMs will more than offset the times the 3.21 has to downshift.
I mean, you said you have never found ANY advantage to taller gearing. Did you even watch the video that was linked upthread? 4 MPG difference and that was, apparently, cruising at 70.
Personally, I NEVER go the speed limit. If you really do spend the majority of your time going the speed limit or less, you are definitely in the vast minority, as far as the drivers I see. My standard is 10 MPH over the speed limit at all times. And I am RARELY the fastest person on the road. Usually, I am just going with the flow of traffic. And that means I am going 80 almost any time I am on an Interstate.
To me, if you have any kind of real towing needs, get a 2500 with a Cummins. The 1500 with ED is for people who rack up miles and want better fuel economy. In which case, you're defeating the purpose if you get 3.92 gears.
I have averaged about 20 - 24,000 miles a year every year for the last 11 years, at least. Since I got my current truck, it's been 2,000 per month. I have had 3.92 gears and a Hemi for the last 11 years. But, I have learned my lesson (finally). My next truck will definitely have 3.21 gears. For those of us that don't do any significant towing, I can't see any advantage to 3.92 gears in the diesel other than take off response from a stop. And when I get an ED, I am very hopeful that GDE or somebody else will have a tuner for me that addresses that particular issue.