Hoping this is not inappropriate, but I'm posting this knowing how difficult it is to get a local GM service shop to recalibrate an ECM/TCM apart from the vehicle. Had I not already gone through the inconvenience and difficulties of convincing the local GM service department to do a few Tech2 ECM recalibrations using a provided benchtop programming harness...
With the recent release of the EFI Connection 58x system for early SBC and late 7.4L BBC engines, we had to get set up for GM TIS-SPS programming to initialize new Gen IV ECMs/TCMs and be able to reprogram used Gen IV ECMs/TCMs with new base GM tunes.
In other words, turn an Impala E38 into a Corvette E38...where the issue is that a full flash aside from a GM TIS-SPS reprogram will not overwrite all calibration segments.
If you are in need of this service, please contact mike@eficonnection.com or visit http://www.eficonnection.com and click on "GM Calibration Services" under "ECU Programming" in the left side navigation.