Student1

I am a student in training to get my CDL-A. Right now I,m having a little trouble with down-shifting smoothly. My instructor says to use the sound of the engine and so far I'm doing a fair job but not good enough job to pass the final skills test. I am hoping someone out there might have some idea of what the shift operating RPM or MPH range is for the gears on a 9-speed Mack CH-600. I'm not sure what the year is but I think it is a 1995 model. Thanks