How possible is this swap ?? (I'm not actually considering doing this right now...but in the future I'd be open to the swap)

Remember, this truck has a a different crossmember and taller frame than the 1/2 tons that this swap has been performed in)

I also know that some of the 3500's got the 6-speed in them...is this the same tranny and is this swap easier than sourcing one from an f-body ??

EDIT: OH, and can you bolt a t-case to the T56 ???

 

if you are talking about the manual 6-speed and no its not the same tranny (99% sure, i know the 6speed manual diesels dont like speedshifting/powershifting and they're not a very close ratio) from 3500s it would probably swap right over

however i would like to personally like to see a 6speed allison tranny swapped in a 6.0 IF they didnt have so much drivetrain loss and cause the 6speed allison has pushbutton shifting

 

i dont know how hard a t56 swap would be but it sure would be nice to see one on a hd

 

The Allison is a weak tranny compared to a 4L80e/T56....It's actually the torque converters that are the weak link but, also, given the drivetrain loss through those things I think I'd rather have a 4L80e

I'm talking about the CAR 6-speed (T56)...I wasn't sure if the truck 6-speed was the same tranny as the car

 

i knew you were talking about swapping in the car t56 6speed


if the allison is a weak tranny compared to the 4l80e then why does gm put it behind the dmax and 8.1L(larger and more powerful motors) and the 80e behind the 6.0L-smaller motor less powerful motor(in stock form) - not trying to sound like a smart *** but i was just wondring and you sound like you might know

 

The Allison is a purpose built tranny...in stock form it's GREAT at what it does, but as soon as you turn up the wick on the motor it starts breaking parts.....ask all the DMax/Ally guys with broken Allisons. Usually it's the TC that goes out...and if you're really lucky it'll spit little torque-converter-parts throughout your ENTIRE tranny in the process

The 4L80e is a factory-freak tranny, it's derived from the Turbo Hydramatic 400 (which is famous for being damn near unbreakable)...I've personally seen stock 4L80e hold 800hp without blowing up. 4th gear is the weak link in these...but if you're racing in overdrive you should be slapped

The reason the 4L80e isn't behind the DMax/8.1 has alot to do with the GM wanting better acceleration and lower RPM's from the DMAx/8.1 at cruising speeds.....the 4L80e CAN hold the power (and HAS in the past behind the 6.5/7.4) but the shorter 1st and 4th gears hurt both acceleration and curising RPM's

 

thanks for the info

hope you find out something on the t56 swap

 

The chevy six speeds are huge **** ZF transmissions(http://media.gm.com/us/powertrain/en...%28ML6%29.pdf), while the five speeds are NV4500's(http://media.gm.com/us/powertrain/en...0%28MW3%29.pdf) from what I understand.

The T56 is a completely different animal. Are you sure that the T56 will hold your roughly 6,000lbs and the HP you plan to throw at it?

 

No....actually I have no idea whether it'll hold the power/weight that I'm dealing with....any ideas ???

 

im sure if you get a FLT extreme duty T56 with viper tail shaft it can handle it...

especially with their reputation