[Bryce lb7]

A 2004 lb7 GMC 2500 crew cab short box has just come into my possession, before I got it the front differential didn't disengage and blew the u-joint in between the front driveshaft and the t-case. That sent the driveshaft flying around and it smashed the trans at 120 kph breaking the shift linkage off and putting a hole in the transmission case behind where the shift linkage is. I want to know if it is possible to put a 6 speed Allison from a newer Duramax and what any problems I would have because I've been searching for a while and haven't found anything on putting a 6 speed into an lb7 truck or any other truck that had a 5 speed for that matter. anything would be helpful, thanks

 

[67msarg3]

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!

 

[Bryce lb7]

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!

Yes but the trans or atleast the case is Broken and I’m looking for a new transmission for it and can’t seem to find one for the specific truck I have so I was wondering about putting a newer trans because there easier to find

 

[67msarg3]

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!

 

[BoiseRob]

NO... The 6spd TCM communicates with the LBZ/LMM/LML ECM.

 

[67msarg3]

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...

 

[BoiseRob]

I want to know if it is possible to put a 6 speed Allison from a newer Duramax and what any problems I would have...

67msarg3... I was answering the OP's specific question (see above)...