I've started the process of building my wiring harness for my BBCad pickup project. I have installed a 7 pin module from a 94 Deville into the original '76 500 large cap HEI distributor. I want to know what to do for a tach input to the PCM. Do I use the tach output on the coil, or is it supposed to be the connection labelled "reference" off of the module? It seems to me that the tach output may damage the PCM. If it is supposed to be the "reference" signal, what do I do with the tach lead on the coil, do I leave it unhooked?