tachometer

I just picked up a simple inexpensive tach for use on my 88 XJ. My dash does not have a tach, just the speedo, gas gauge and assorted small guages. What I was wondering was this: Do I have to run all the wires to the engine compartment, or is there a tach lead in the dash for the optional tach that I could tap into?

The wiring is already there if you swap in a cluster with a factory tach, so most likely you could tap the correct wire at the back of the cluster. I'll try to decipher the electrical manual to determine which wire feeds the factory tach.