3rd Gen Engine and Drivetrain -> 2007 and up 6.7 liter Engine and Drivetrain discussion only. PLEASE, NO HIGH PERFORMANCE DISCUSSION!

MT vs. AT

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Old Nov 25, 2008 | 09:38 AM
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From: The Great Republic of Texas!!!
MT vs. AT

I have a question about the differences between the 2 trannies. A friend of mine bought a new 3500 with the 6spd auto and says that its rated higher than the 6spd manual. Is this true?
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Old Nov 25, 2008 | 11:08 AM
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The engine is derated on trucks with the manual transmission. 325 vs 350 HP.

Why? Speculation is that the MT has a weak clutch.
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Old Nov 25, 2008 | 11:21 AM
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From: The Great Republic of Texas!!!
thanks for the info
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Old Nov 25, 2008 | 02:02 PM
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From: Sand Gap, KY.
Originally Posted by sabersix
The engine is derated on trucks with the manual transmission. 325 vs 350 HP.

Actually, the HP is the same 350/350...........the torque is de-rated from 650 (auto) to 610 (manual).

Greg
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Old Nov 25, 2008 | 02:46 PM
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but is there a difference in which tranny is rated higher for towing capacity. also, what is the low range ratio in the auto tranny?
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Old Nov 25, 2008 | 03:03 PM
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Just to add to the confusion,I thought the difference in ratings was only on the C&C trucks?

I thought the pickups were rated the same.
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Old Nov 25, 2008 | 03:34 PM
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From: Redding, Ca
Originally Posted by gsbrockman
Actually, the HP is the same 350/350...........the torque is de-rated from 650 (auto) to 610 (manual).

Greg
This is correct for 08 pickups at least.
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Old Nov 28, 2008 | 12:04 AM
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From: Victor, MT
Originally Posted by jlau6888
but is there a difference in which tranny is rated higher for towing capacity. also, what is the low range ratio in the auto tranny?
I don't remember the exact figures offhand, but the final drive ratio of a 6.7L-equipped G56 with 3.42 differential gears is nearly identical to a 68RFE with 3.73 differential gears.
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