GMC Repair: Harsh 1 to 2 upshifts, hydralic, engine diagnostics

Question
Hi Pawl,
Could you please sent me the latest program # dealing with intermittent harsh 1 to 2 upshifts in my 1999 Silverado (see prior contact information printed on your site 9/5/2007) and any information you might have gained talking to your transmission tech. Two years ago, the PCM was reprogrammed with # 16264212.
Thank you for your time. Appreciate it.
Regards,
Peter

Answer
Hi Pete.
Here is a list of ALL the newest calibrations for your truck
9379910 - Operating systems
9358570 - Engine
9357937 - Engine Diagnostics
16264212 - Transmission
16264357 - Trans Diagnostic
9373427 - System
I Have all this printed out. My tranny tech said if fuel filter did not help "look for trash in the valve body feeding the making the valve stick for the 1-2 shift accumulator." "Check the 1-2 accumulator"
He said MOST problems will be in the valve body (hydralic circuits)
Please follow post back if needed.
Good Luck and thanks
Pawl