crbr said:
Right..... Here's a message for your source... What he sees on the rollbacks is not what makes the world go around, although one has the choice of belief...
I started out with the LB7 in 2001. Go figure...
Here's the scoop. Take it or leave it.
It is not the Allison, but GM has regionally recalled the air pipe connected to the Mass airflow sensor & redesigned it. The northern tier dealers said they gets 2-3 calls a day. It turns out a sensor is freezing up inside the pipe & GM will replace the pipe & sensor with a new design. The frozen sensor causes the truck to go into "limp mode" which feels as though the tranny is having issues.
GM will repair according to "region" I was told. (I assume this means if you are in a cold environment).
Owning a diesel and watching rollbacks .... I'm just saying....
....
FWIW...I'll leave it
KAB is correct with what he posted. In addition, this -transmission- issue does not apply to 05 and older due to a different cooler function.
Here's something straight from the horses mouth

...a copy of the letter I received
December 2007
Dear General Motors Customer:
This letter is to inform you of a condition that can occur in your 2006-08 Chevrolet Silverado HD or GMC Sierra pickup truck when air temperatures fall below minus 40 degrees (-40ー C/F) (excluding wind chill). If you do not operate nor expect to park your Silverado or Sierra outside for extended periods in far northern or western plains regions where temperatures may fall below -40ー C/F, no action is necessary.
We have learned that your vehicle may have limited or no transmission fluid (oil) flow through the transmission oil cooler after sitting for an extended period of time, such as overnight, during extreme cold temperatures -40 ーF or ーC or less. If the "Elevated Idle Mode" cabin heater performance option is operative and the engine is allowed to idle for an extended period of 15 to 30 minutes while cooler flow is limited, the transmission fluid may overheat, resulting in transmission damage, and subsequent failure.
Your satisfaction with your 2006-08 Chevrolet Silverado HD or GMC Sierra HD pick up truck is very important to us, so we are announcing a program to prevent this condition or, if it has occurred, to fix it.
What We Will Do: To prevent this condition from occurring, your GM dealer will reprogram the Transmission Control Module (TCM). This service will be performed for you at no charge until February 28, 2009.