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switch a four speed for a six speed


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#1 Vermontah

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Posted 15 April 2012 - 12:06 PM

i have a 05 2500hd silverado with the 6.0. I love the truck. I bought it with 94000 and now it has 145000. It has been flawless. The tranny just started to like from the front seal. Nothing to bad, maybe a 1/2 quart a month. I'm in a wait and see pattern right now. I dont think its anything to panic over. However if it gets worse and I have to pull the tranny to replace the seal i will think about putting a remaned tranny back in its place. That said I will get to the real question. Is it possible and what would be involved in replacing the four speed with a six speed out of a newer truck. I am thinking the six speed would help with mpg especialy on the highway. thanx for all your input

#2 MedicPilot

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Posted 15 April 2012 - 12:22 PM

Yes,anything is possible. It would require a new ECM as the transmission is controlled through it. Would also require a different shifter as the new 6 spd has a manual mode. Would not be worth the cost to do it all. Not sure if the transfer case is the same in both 4/6spds either, so that would be another issue. Overall length, and drivershafts could be an issue too. I dont think you would gain enough MPG's to ofset the cost of doing it.

#3 music

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Posted 15 April 2012 - 07:54 PM

I wouldn't do it. The 4L80 is a solid transmission, and all you gain on the 6-spd is a super low granny gear, and the extra overdrive. Gear ratios @ 2nd,3rd,4th,5th on the 6L90e are very close to 1/2/3/4 on the 4L80. The conversion would never pay for itself in fuel savings.

Edited by music, 15 April 2012 - 07:58 PM.

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2008 GMC Sierra CC Z71 4wd


#4 govtech4

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Posted 15 April 2012 - 08:43 PM

Yes,anything is possible. It would require a new ECM as the transmission is controlled through it. Would also require a different shifter as the new 6 spd has a manual mode. Would not be worth the cost to do it all. Not sure if the transfer case is the same in both 4/6spds either, so that would be another issue. Overall length, and drivershafts could be an issue too. I dont think you would gain enough MPG's to ofset the cost of doing it.


+1000 !!!!

well put Jeremy !!
How do you write a signature on a laptop screen ??

lmao.


I'm here all week ,try the Veal !!


Rob




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