You do not need a tach drive in the 96-98 Mustangs. I use to have a tach in mine. All you do is pull the guage cluster out and splice into the wires. It has been so long since I did it. The source, power, and lighting can be hooked this way. I do remember that you you use the right side plug harness. Do a search for it. There is a post on here somewhere telling you which wires to use. Good luck with it.