u have to have a tach driver in order to connect a tach or shiftlight up to this motor. you do know this correct? if so then it should be pretty self explanatory from there if not send me a PM and i can give you more detailed instructions.....
EDIT: didnt pay attention to the 98 was thinkin it was a 99, my fault and you do not need a tach driver in this case
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.