Duramax vs Power Stroke Fuel Economy Tow Test and Drag Race

Cummins12V98 wrote:
Dead flat no wind conditions towing 29k combined thru Salem, Oregon on I-5 I would get the exact same mileage in 6th at 62mph as 5th. Once getting farther South around Eugene where the road started getting into the small hills It would pop in and out of 5th. I compared that mileage to locking 5th and 5th was a bit better. I finally just locked out 6th towing at 62 and would have my rpm's at around 1,750 and it performed flawlessly dropping gears as needed. With the 68 I could drop a gear once rpm's started dropping trying to hold my speed on a steep grade. Sometimes it worked and sometimes it made no difference.

With my 4.10's AISIN I tow in 6th same RPM as I did with the 68. I have tried dropping a gear once it starts loosing speed and it just stays where it needs to be and shifts as needed. It simply knows where to be.

They both worked great towing heavy but the 3.42's needed the lower starting gears on a grade the AISIN gives.

ONLY change to the AISIN I would like to see is the ability to lock out first and start in second while unloaded.

This has more to do with your 4.10 gears than it does having an Aisin. I would wager that a 4.10 68RFE would be the same since they both have the same 6th gear ratio although the 68RFE has a better 5th gear than the Aisin. Also, since the 68RFE has a 3.23 first gear instead of the 3.75 on the Aisin, I would bet that you would not want to start off in second gear.