Initial flash of T42

Replacing the transmission controller on a 2008 Silverado, I uploaded the calibration from my old one and tried to flash the new one but got an error saying the OS was different. Do I have to find a newer calibration to match the new module? I've been looking around but haven't found anything. Thanks for any help or advice.

EDIT: I think I need a T42 stock tune (2008 Silverado) that uses OS 24252617. If anyone can point me in the direction of one I would appreciate it, thanks.

I've tried it many times with no luck. The OS is pre programmed into the controller. GM MDI and TDS web is the only way to do it on your own. I trailer them to a dealer when I rebuild transmissions and /or replace the TCM.
I think I've still got a flat spot on my forehead from beating my head on the wall trying this one over and over.

Thanks for the reply. I had to get a controller from a third party, programmed to my VIN.