Allison 5 to 6 speed conversion

I have an 04.5 Duramax with the Allison 5spd. I was tired of my mileage dropping and temperatures rising if I went 75mph or more.

I couldn't find any good videos of the install or results other than 3 from Duramax Tuner themselves and one random guy in his garage. So I did this video to hopefully answer any questions others might have about the install or visible results from someone else.

So I installed Duramax Tuners 6spd conversion kit. Very easy install, about 2hrs, and so far a lot nicer ride

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[chadbailey]

great video, explain everything well!!
I was blown away with your info ! never knew you could do this!!!! first for me!!
I'm going to leave my trans alone thou, if it's not broken don't fix it!! lol

[enrique]

Yeah ok video most grateful for showing us the differences between the 5 and 6 speed valve body.

[RiggyRonnie]

That’s mind blowing, how do you make a 6 speed transmission but only let it run 5 speeds from the factory?

[megastick]

I thought hard about this a couple years ago for my 02. By the time I figured up any fuel $ savings vs cost I don’t see a break even point.
I drive all over the country towing a TT, and it just doesn’t show me a savings or gain. After doing the math, I would be better served with a newer truck with a 6 already in it. Or an engine/trans swap to newer, lower mileage when the time comes.
Each to their own though I say.

[rooster]

I got a lb7 03 classic love the od lockout if need be but cone spring ill definitely be doing this swap. Im pulling 24 mpg city and 28 interstate but yes drive and 75 or 78 mph the conversion kit for 6th just makes the sense 1900 rpm is alison butter. But thanks for the video cant wait to get this done

[nicholaskoelkebeck]

Great video. Have you towed or added power back yet, will it stay in sixth while slightly loaded. I assume LLY Engine temps rising is the head issue? Not normal in my LB7, only time is climbing mountain at 70mph with 8, 000 horse trailer in tow. Climbs to 210 degrees and holds up till the top which is 1500ft rise in a few miles.

[bravojuan]

What was the valve body brand or name of kit you used?

[troymayfield]

So now that you've had this for awhile do you still like it? Still shifting and holding 6th well?

[jamesdeanvegas]

So.i know Duramax tuner has this its very pricey. Why can’t u just install a valve body from a 6 speed and the tcm? Just curious

[joeesparza]

I have a ‘03 GMC Duramax
Lucky to find a truck with 49, 000 original miles . I’m interested in conversion .
Who supplied your kit ?
See those rpm ‘s drop was something .
Currently at 2000 I’m running at 65

[MehIlvin]

U happen to have any issues in regards to the cluster im having it read my transmission temp at 305 degrees but i know for a fact its not, is this part of the learning process

[wesfoley]

How much fluid did you need to put back in? Does Amsoil have an approved fluid for this?

[casanovazombies]

Just wondering have you had any problems with this conversion kit in your transmission? And what fluid did u use

[conradsenior]

is there a different wiring harness internally?

[takemebackpetersjakob]

Douse it still down shift in tow Hall and down shift again if you hold tow Hall for a long time until the overdrive light comes on

[thomasgriffith]

Will this kit work with a 5 speed Allison bolted to the 8.1 gas engine?

[NashvilleGrille]

Are those replacement parts Allison? If not, who makes them?

[thecerealcommie]

Where did you buy the kit from?? Also what is your new MPGs?

[davidmartinez-gikp]

So your telling me all I have to do is change the these two pieces and boom 6speed trans

[_Rubicnn]

How was 5th to 6th gear shift for you initially? Mine seemed a little harsh at first...