Sorry cRiPpLe, I missed you post, still working on getting all of my notifications figured out.
I have a 2006 Chevy Silverado, 2wd, 4.3, AT with rubber floors and crank windows.
The tune by blackbear performance really helped with the fuel mileage, mostly trans tuning. The TC used to lock up at 46mph min, now it will lock up at 34mph with no lugging
Here is a pic of it halfway between summer and winter tires.