Anyone know what the limits are of an Autotrac transfer case. I'm looking at an 03 EC Sierra Z71. Also, I know I could do a 4l80 swap, but would there be any conflicts swapping over to a manual transfer case out of a HD truck while doing an 80e swap?

 

They can take a good beating. Parish ran his well into the 600-700 hp range I think, never broke it.

If you change the input gear on the transfer case you can get it to mate up to a 4L80E just fine. That's what I did. I wouldn't bother converting to a manual.

 

I've noticed on several trucks belonging to friends that they commonly have a problem with 4wd enguaging, and service 4wd messages on random occasions. It seems to come and go. One in particular being an 07 classic doing this, the dealership has yet to find anything wrong with it. These occurances make me skeptical of the autotrac.

 

Weird, I have never once had a problem with mine. I have 134,000 miles on the truck too.

 

I had one 4wd error message about three months after I got my truck (still under factory warranty), it had less than 30,000 miles on it. I guess there is a wire that comes un-soldered in the controller? I've seen a few people post up about it here, but mine was already fixed so I didn't pay that much attention to them.
Any how almost a hundred thousand miles latter, 60,000 with a turbo, I have yet have one bit of a problem. I drive my truck everyday. About 250 miles a week and there is rarely a day when I go with-out shifting the autotrac into 4wd for a little stop light fun......