Try some lucas transmission fix, good stuff

I found the problem. I had my tranny fluid changed by the chev dealer. The truck is 4 wheel drive so you do not have a straight shot with power tools to the side of the tranny pan with the front drive shaft. Half of the bolts on the tranny pan on the side of the drive shaft were were cross threaded and not tight. I took the cross threaded bolts out and worked them down from the tranny towards the pan or the ground. There was enough of a thread left on the top of the hole to straighten out the threads on the bottom of the hole.

Many hours of work to fix a problem caused by someone in a hurry with a air gun. I bought the truck new and the chevy dealer has been the only one to change the tranny fluid.

I guess you are better off not changing the tranny fluid.

Thanks

Keep trans full or fluid!
Check monthly. Keep an eye out for leaks.

The quickie lubes have a trans fluid changer that pulls the old fluid out the cooler lines and puts in new fluid. Backflushes filter. Not as good as a true pan/filter removal reinstall, but sounds safer than using your dealer!