I have a 1999 Blazer that I just recently swapped in a reman 350 from a 96-98 k1500. I had Current Performance modify my stock harness to work with the new engine without changing the Blazer around, and they also reprogrammed my stock computer. My tach does not work right now, yet it does read on my "scan tool". I still have to relearn my Crankshaft Sensor Variance and I think that is why it doesn't read right now. The thing I'm more concerned about is that I keep reading that after it is reading it will read off by 33%. All the info I can find is for the older first gen s10's and blazers with instructions how to increase the size of the capacitors. I would like to know if anyone knows how to modify a newer tach to read right. I know there is a re-calibrator out there that will do it for me, but that's a lot of money when I can fix it with a cheap resistor or capacitor.