I ran mine right to the ECU harness itself, and tapped the tach wire there. Wasn't hard at all...

I could've just done it behind the gauge cluster as said, but I didn't think of it when I installed it a few years back.

99 Cougar V6 MTX...Plenty of mods My best mod thus far: Trans: Brand New MTX-75 with B1 gear set, Quaife LSD, 4.5 Final Drive, Spec Stage 1 Clutch, Spec Aluminum Flywheel...