i need access to a dimmer wire for my new tach. which one off of the dimmer switch can i use? or is there a better spot to tap into? my tach is going in the stock location if it helps at all.

 

You could tap into the INST fuse (is powered from the wire comming from the dimmer on the light switch) on the fuse panel or the grey wire at the cluster harness terminal. You could also strip the wire insulation off enough to stick the bare wire into a cluster bulb socket and then plug the light back into it (the bulb socket) and reinstall the socket to the cluster for dimming/lighting power (don't know if that last one made sense to you or not..).

http://92b4crs.tripod.com/86wiring/dia-pics/117-0.jpg
(drag & drop this link into your browser addy bar to view)
That may help you see a little of what I'm talking about.

 

can it be ANY light, or does it have to be the ones that go one when you turn your headlights on? i was thinkin bout the light under the dash, but thats only on when you open the door or turn the interior lights on. i was thinking about soldering the wire to one of the bubls on the cluster, but that just doesnt seem to reliable. ill probly just tap into that one gray wire. thanks for the help!

 

If you're wanting the tach to be able to dim with the dash lights, it will have to be on the same circuit as the dash/HVAC/radio (instrument) lights which is the INST fuse.
The circuit gets it's power from the light switch dimmer itself, is fused at the panel (where it changes from a green to grey wire for some reason) then branches out to the instrument lights. If you put a tap at the fuse, the light in the tach will work as if it's one of the instrument lights.

If you hook the tach up to the orange light on the courtesy (floor and dome) light, it will be on all the time. Switched grounds is what makes the courtesy lights come on.

 

ok, got it. thanks alot for yor help!