Hi all,
I am buttoning up my 2006 EnvoyXL engine build (2005 4.8, rolling thunder cam, headstuds, and s366) and its time for the trans swap.
Transfer case is a part time, 4 position selectable NP8 or 226.

As I understand, I can use my PCM/TCM and swap a file with HP (which I am very new to).

Physically, what do I need to keep my transfer case and make it work? I have a adapter harness for it already, and I have NOT bought a converter yet, i think i can get one with the longer hub to fit my 4.8 flywheel. Driveshafts I can handle. Mainly looking for advice on either being able to use my transfer, or swap with a different one that will still shift like stock using the inside factory electronic ****.
thanks!
mike

 

Any particular reason why you're going with a 4L80?
It's kind of overkill with a 4.8 and a smaller truck.

 

The output shaft splines on a 4L60e and 4L80e are different. The transfer case will have to be dissembled and a hub with the correct splines will have be installed. Lawrence LT Tolman did this on Power Nation and his own YouTube channel. He had found a company that made the conversion hubs.

 

well i have a good “stock” rebuilt 4l60e, and a box of billet parts to go in it.
The Envoy is lifted running 33’s, and its the long version, fully loaded comes in at 5100lbs. We are gonna use this as a “trip-taker” and I’d like to be able to pull a trailer down to see our son (stationed in NC) which takes us through the mountains, and other various vacation type stuff. Plus beat on it every now and then and not have to worry. It should conservatively put out 500hp, so with all the above, I dont like relying on a 4l60e.

i have no issues replacing the input in my transfer, i have done that before in other situations, i will track that part down, thanks!

 

I have done this swap.

https://www.allstategear.com/NP246-T...shoppingengine

thats the input stub gear. there were a few 241/246's that came with a 32 spline input but I havent come across one in person. Supposedly in the 04-05 1500"HD" that came with the 80e, but half ton axles.

you may also consider the np263. The harness plugs will be different and the OS for the trans control will be different as well (same story going from a 60e to an 80e)

My preference for doing this swap in tahoes is the 261 and a manual floor shifter.

and in any t-case you buy, either do the pump rub mod or make sure it's been done. all three models i mentioned have that issue.

and all three can absolutely hold the kinda power and weight you'll make.

good luck. 4wd high gear burnouts are frickin awesome

 

hmmm i have a few 241/242’s maybe those have it..
i’d love to go floor shift, but these Envoys dont have any room to do a floor shifter unless i cut out the center console. I want this to be pretty much “stock” operational wise.
The hub swap would be perfect.

I was gonna swap to 4.10’s, but i figured the larger tires, the higher gearset of the 80e, and my 3.73’s should load the turbo pretty good. Cam is on a 110 centerline and makes power from like 1500-6000. Im hoping it will have the power to blow the tires at a 20mph roll. All my larger vehicles are usually diesel, and any other turbo vehicles have been cars…
this will be my first turbo lifted gas “truck”.

 

what about an NP243 swap from a OBS w/ 4l80E and swap in the module & buttons for the push button shift?

I want to do an NP241 out of an OBS into an escalade and just custom fab the handle to come through the side of the console, tight to the side.