It just so happens that I have a Haynes manual for a S-10, but......it does not mention anywhere in the whole book where to hook up a tach!!! Even the wire diagram of the instrument cluster doesn't have a factory tach. It does talk about hooking up a hand held tach for idle control on a carbed engine, but says to follow the manufacture's (tach) recomm :therethere:endation on where to hook it up. Sorry!
