I have installed a 84 Z28 instrument cluster in a 80 Buick Regal (custom dash). I've managed to get everything to work with the exception of the tach. I'm going to try the resistor fix for the tach tomorrow (it is pegged) but since I do not have the camaro wire harness, I do not have a tach filter. I'm running a non CC HEI distributor. The question is, is the tach filter needed? I was running an aftermarket tach without a filter and it of course worked fine. If the resistor fix works then my question will be answered I suspose. But again, do you think I need the filter to make the tach function properly? -thanks