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Discussion Starter · #1 ·
Anybody know what they are for the forward gears? I wonder if it's just a lower overdrive or whether the lower gears were changed any.

Doug
 

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Nope, transmission is PHYSICALLY identical to our 5-speed's. Only change is the addition of a bypass tube in the valve body to allow actuation of "6th" gear (which in reality is just a different combination of the same 3 planetary gear sets and clutchpacks) and different TCM programming. Reverse, and 1st thru 5th gears are exactly the same...6th gear is just a "double over-drive", designed to drop RPM's when cruising unloaded. I doubt it'd be useful towing tho, its geared too low. I think Tow/Haul might lockout 6th gear. In that case, it would be identical to driving one of our 5-speed M74 Allison's.

----Ben
 

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They are pretty much doing what companies like gear vendors and us gear have been doing for years. They are giving you a taller overdrive to reduce RPM's. I find this funny since all the manufacturers dogged the aftermarket overdrive companies saying they bogged the engine, yet they are now doing the same thing to achieve the same basic goal.
 

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Discussion Starter · #5 ·
With the new freeway 6th gear, can you now get .410 gears as an option for the 2006 Duramax?
 

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I am pretty sure you can still only get 3.73

I personally wouldn't want higher gears. You're still only going to tow in 5th not 6th.
 

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I am pretty sure you can still only get 3.73

I personally wouldn't want higher gears. You're still only going to tow in 5th not 6th.
Actually tows really good in 6th gear. In tow/haul mode, it shifts into 6th at about 63mph under light throttle and it takes a decent sized hill and a loss of what seems like about 4mph to make it downshift to 5th when in cruise. :cool2: In normal mode, it shifts into 6th at 53mph under light throttle.
 

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[I am pretty sure you can still only get 3.73]


But if you order a dually you can opt for 4.10's
 
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