Wide Open

Trying to solve a problem.
I have a 00 RCSB originally with the Autotrac transfer case. I am swapping to a 6L80E and the output shaft of the 6L80 is larger than the 4L60. I have a 07 AWD transfer case that will work but I would like to stick with the Autotrac if possible. I do not want to switch to a smaller output shaft to match the Autotrac case. So here are the questions:
Can the input shaft of the Autotrac case be swapped with the input shaft of the AWD case?
If not, does anyone know if I can have the Autotrac shaft swapped to match the larger 6L80 output shaft?
If I stick with the AWD case does anyone have a front AWD differential with 3.73 gears they want to sale?

2004SSS

iTrader: (25)

id look into the shaft the sierra denali uses. btw how are you gettign the 6l80 to work?

Wide Open

I have that shaft in the Denali/Escalade transfer case but would like to get some answers to whether or not that shaft will work in my original Autotrac transfer case.
I am getting the 6L80 to work with the original 07 E38, 6.2L with DBW, and a custom harness from an LS1Tech sponsor. I haven't had my truck out on the road yet since I have some unresolved transfer case issues but the company I am getting my harness from has. Their project truck is a 2wd drive model.

kbracing96

iTrader: (26)

If it has the same output shaft that 4L80 has, Speed Engineering makes a input shaft for the autotrack TC that will fit it.

+1 on wanting to know how your making a 6L80 work

2004SSS

iTrader: (25)

you have the one from the gen 4 elade or denali?

Wide Open

See above regarding the 6l80. I will identify the company after I talk to them again tomorrow.

BTW, does anyone know how the 07 AWD transfer cases operate? I have heard traction control, which my truck doesn't have, but I have also heard they have a viscous coupling. When I turn the input shaft the rear output shaft turns as if it is mechanically connected. The front shaft turns however I can stop it from rotating with only my hand. It doesn't have any fluid in it at the moment so I am wondering if it doesn't work properly until fluid is added.

Wide Open

Are the 07+ the GenIV models? If so, then yes that is the one I have.

Wide Open

What is VERY odd about this is my rear driveshaft is a perfect fit to the 6l80 output shaft. So why does the 4l60 output/Autotrac input shaft neck down and then go back up on the output side?
My original front driveshaft also plugs right into the front output of the AWD case.

1slow01Z71

iTrader: (36)

I have an AWD front diff with 4.10s if you have to go that route.

Lord Aries

iTrader: (6)

I know part of the answer... The 4L60e uses a 27spline Out put shaft going to the transfer case and the 4L80e uses a 32spline shaft... So when you do the 4L60e to 4L80e swap you have to either get a 4L80e with a 27spline out put shaft or change the input gear in the t-case to a 32spline gear.

Why do they do this? Who the hell knows, probably saved GM .03cents on something by doing it...


P.S. will the AutoTrac t-case even bolt up to the 6L80e???