General guidelines for tuning GM vehicles:

Uses .CRG or .2CL file formats, 2CL to be used in Predator only. 1999 SOFTWARE C. This is the most recent calibration from GM for both 1999 and 2000 year vehicles, if the vehicle has been flashed recently (late 2004) it most likely uses this template. Uses .CRG or .2CL file formats, 2CL to be used in Predator only. 2000 SOFTWARE A ................
................