2000 Yukon XL 2500 Trans Problems

Lately my gas milage has been slipping and I think so has my transmission.

I have the 6 liter engine with whatever transmission attaches, 4wd..

I searched the GM records and the previous owner had 4 transmissions replaced in 120000 miles. Is there by chance something wrong with these or is there a way to make them bulletproof?

:banghead: Not a happy camper and any help would be appreciated.

Hi, the 4L80-E is a strong tranny and can take more than what the 6 liter engine puts out.
It also is used with the 8.1 liter engine.
My 2001 YXL K2500 has 100,000 miles on it and I tow an 11,000 lbs camper.
Transmissions usually are rebuilt and not replaced.
There may be something specific to your tranny.
Also keep in mind that it is governed by a computer, the TCM.
Maybe that should be reprogrammed. :dunno:
I only know a good tranny shop in Manchester, CT and one in Vernon, CT.
Both are run by 'older' guys (like me) with a wealth of experience (unlike me).
I hope you find a good one in your area.
Take care, Eggert :bananasmi

My 1991 2500 7.4 with the 4L80-E was replaced in 1995 with 60K miles with a new tranny from the factory as a recall defect possibility.
BUT, last month the 1995 tranny started failing at 65K miles, the overdrive (4th Gear) is slipping with a code 68.
When I started talking to a local dealer about a replacement tranny drain plug,he tried to pull up the specs and the tranny that supposed to be there does not have a drain plug on the transmission. He looked up the one ton vehicle and found the drain plug. It's back ordered.
The transmissions should last more than 60K miles.
Does any one know, is the 4L80-E the same as on the 3/4 ton?

My 1991 2500 7.4 with the 4L80-E was replaced in 1995 with 60K miles with a new tranny from the factory as a recall defect possibility.
BUT, last month the 1995 tranny started failing at 65K miles, the overdrive (4th Gear) is slipping with a code 68.
When I started talking to a local dealer about a replacement tranny drain plug,he tried to pull up the specs and the tranny that supposed to be there does not have a drain plug on the transmission. He looked up the one ton vehicle and found the drain plug. It's back ordered.
The transmissions should last more than 60K miles.
Does any one know, is the 4L80-E the same as on the 3/4 ton?
I have a 1996 Chevy Sub K2500 7.4L 4L80-E. I had my tranny rebuilt at a local shop last year. It had about 160K on it. The mechanic couldn't believe it lasted that long. It had the same symptoms as yours (slipping in OD). The mechanic said that the 4L80-E was a redesign of an older transmission that had wear problems on several components. In particular there is a valve body that is aluminum with a ceramic coated valve that causes wear in the valve body and allow fluid to leak past the valve and not allow the preassure to stay up that allows it to stay in OD. He said GM knew about these problems, but choose not to fix so the transmissions would need to be rebuilt or replaced (usually at around 60K). This is just what the mechanic said and may not be the same situation as yours. Hope this helps.