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Junior Member
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36 Posts
Discussion Starter · #1 ·
Hey guys! i have an 07 5.9 cummins with the not so good automatic. i was just wondering how everyone is liking or not liking the new six speed auto.? I haven't really heard anything about it! cuz I was thinking about possibly replacing the junk 3 speed with a 6 speed if it's even possible. but then if i did that, would i have to use a computer out of an 07.5-08? then that probably wouldn't even work with the 5.9 motor, would it? You guys know what I'm getting at. Hope to get some answers! thanks!!
 

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Senior Member
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2,655 Posts
Got enough money for a 6-speed........then build what you have. A built 48 will hold MORE HP & TQ than a 68. (Sun Coast)
 

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the only problem with a built 4 speed............. is that it is still a 4 speed. Big gaps in the rpm range with a 4 speed unlike the six speed. I would love a six speed.
 

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Senior Member
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2,655 Posts
Problem isn't running down the road it's getting the load going. 1st gear just isn't low enough. 3 and 4th work just fine with a 3:73 provided you have enough 'extra' power. (something above stock, say an extra 100hp and 200 tq)
 

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38 Posts
To answer your fist question, i like the 6 speed. Shifts into 5 & 6ths gears early, however if your towing, the tow/haul fixes that problem, Not sure how you would impliment it into the 5.9 and all the electronics and what not.
 

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Let it all Ride
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1,316 Posts
I gotta say, I like the 68re a whoe lot better that my 5.9 with the 48. It is has a lot better driveability and seems to find the right gear more consistantly.
 

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432 Posts
my 6 speed is great cruising the interstate empty as for fuel milage. playing around on the race track - i like that there isnt much of a rpm gap between gears........ pulling - love the low gearing to get the load moving.... the 68 is a great tranny
 
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