How to tell if Allison is MW7 or M74?

[Boostlee93]

I know this may be a dumb question but ive been searching for an hour with no luck.

How do you know the RPO of an ally if you dont know what year duramax it came out of?

Heres the specs

Serial Number 6320295816 Model Name 1000PK
Engineering Groups

Component Number Description 01-778 MAIN HOUSING GROUP-STD 10-648 OIL PUMP GROUP 14-1073 STD W/PTO DRIVE GEAR 16-1792 CONTROL VALVE GROUP 21-915 CONVERTER GROUP - TC211 34-580 GM DIR CONV HSG, #8 PORTS, 7/8 THD QC 37-587 OIL PAN GRP - SHALLOW OIL 39-842 1000,CR,W/PPWL,W/O P BRAKE,GMT800 4WD



Any help would be great!

 

[blk smoke lb7]

01 02s have 3/4 trans line adapters 0304 have 7/8ths and the 6 speeds i guess the trans line adapters are in a differant spot.What do those codes stand for?

 

[Boostlee93]

So this tranny is a 5spd? I mean i know they are all 6 speeds technically but i want this tranny to get built and then swap into my 05. I just want to make sure its not 06+ before i send it off to get built.

And for the codes M74 is 5spd and MW7 is a 6spd....well thats what i got out of my research anyways. I think i remember Ben saying you find the code in the glovebox of the truck or something? But of course theres no truck attached to this tranny. lol

 

[TeaBagger2006]

Easy way is to See if the nsbu switch(little black box where the shifter attaches) is inside or outside the trans

Outside=5 speed internal=6 speed

 

[Boostlee93]

Perfect, thanks!

Will check for that in the morning.

 

[blk smoke lb7]

An 05 lly trans has the bigger input and output berings like the 06 i believe 04.5 lly could have both small front and rear berings or large front bering only and the lb7 transmissions are all small bering front and rear.or so ive been told.As far as the codes not sure.

 

[GMC04DURAMAX]

So what's the big difference between an 01,02 ally and an 03,04 ally?

 

[Boostlee93]

01-02 has the different housing, hoses, and bearings. 03-05 has the added g solenoid and a few other things I can't remember.

Don't quote me 100% on that though as Im no tranny expert.

 

[jc1843]

The 6 speed will work in place of the 5 speed-- BUT you will need the NSBU switch, valve body, and internal wire harness from the 5 speed. Of course you will only have 5 speeds. The 6 speed internals are stronger.

 

[Boostlee93]

Thanks guys, turns out it is a 5 speed. Found the switch on the outside this morning.

 

[LBZrcks]

Another way I noticed is the 5 speeds have a silver tag/plate and the 6 speeds have a black tag/plate on the side.

 

[Boostlee93]

Is there anyway to tell the specific year the tranny came out of? Not really a big deal i guess but its always good to know.