The stock Duramax puts out like 600 ft. lbs already now....so when people start turning em' up thats' what kills them. Once you do the Suncoast upgrade, everything seems to be fine for big HP/TQ numbers. I don't think the T-56 stands a chance in a 4wd 2500 truck. The truck 6 speed and the T-56 are not the same, not even close.

 

The inputs shafts are different between the GEN 1 and GEN 3 T-56's are they not?

I always thought that when installing a T-56 into a truck that you are supposed to use a 93-97 F-body T-56 in an 88-99 old body style GEN 1 TBI and GEN 1E Vortec engine truck, and a 1998-2002 Fbody T56 in a 99+ GEN 1 engined truck.

I am pretty sure that the GEN 3 engines have a bolt at the top of the tran bellhousing and are missing 1 bolt on the passenger side IIRC. Even though the other bolts and the engine/trans dowels are in the same position.

You can bolt a GEN 1 engine and a GEN 3 trans together but you cant use all the same bolt holes.

Are you using a 98-02 or 93-97 T56 in you 4.8L GEN 3 engined truck??

Thanks for giving up some info I have always wondered about.

The weight between a rc sb or an ecsb is MUCH lighter than a 2500HD truck which is roughly 6000lbs. A maximum effort T-56 trans would be needed to survive, a Vette or F-body T-56 wouldnt stand a chance with any decent torque or power in a drag race situation.

Allisons can be had that are rated to 1000 hp and 1000 lb/ft, the cost, $5200. The Allison trans used to be used in school busses. We also used different Allison automatics in Freightliner tractors.

peace
Hog

 

FWIW a guy on syty.net forum is running a 6sp with decent luck so far. Im not into doing a AWD/6sp conversion so I havent followed his build much but some digging around should turn up some info.

http://www.syty.net/forums/member.ph...astposter&f=32

 

You are right about the 93-97 inputs shafts being different from 98-02 but I am unsure of the differences in the tail of the cranks on the 8.1L's vs gen1 sbc, or gen 3. They use the 4l80e as well but not sure of the differences??? Aftermarket T56's can be purchased that bolt right up to the gen1 belhousing.
The gen3's use the top center bolt hole that the first sbc's use to use but not all belhousings have the upper right tab. I am unsure of which holes are missing/ not used with the 8.1L? In a worst case scenario you would only have 5 instead of 6 bolts in which should be enough anyhow.