5" Tach with shift light mounting?

You need a tach adapter since you have the cop. It will not work otherwise.

But the red goes to a + wire that is hot only when the ignition is on. The white goes to your light switch or any source that is + only when the lights are on. Green you will plug into the tach adapter and then you have to wire the tach adapter.

You can get the adapters at www.dallasmustang.com and I think FRPP sells one too.

My website has a tech write up of when I installed one on my Cobra. Like 04 said, you will need a tach adapter.