From what I have read, your 2004 Alison is already a 6 speed. you just have to buy the conversion valve body along with getting the Transmission control module remapped. i'd say it's a 2500 to 3000 upgrade but the trans itself already has the gears!
From what i have read, they are the same transmission. However, you would most certainly have to get the TCM reflashed. Just search 5 to 6 speed conversion and you'll find all the info you need. it will be my next upgrade after i sort out the fuel in my oil!
I'm quite positive that if he was able to rebuild his LB7 trans and then install the upgraded valve body and then have his LB7 TCM reflashed, he would have his 6 speed Allison. just sayin, no expert here...
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