Tach problems-no signal?

I recently installed a tach in my car, i was using the autometer tach adapter, i sure they work the same though. Here is the directions a guy from autometer gave me.
" Locate the large, square, 42 pin wire harness connector on the passenger side firewall. Look for pin #34, which is usually located towards the corner of the connector and is usually a solid red or red with a green stripe wire. Cut this wire in half and wire in the tach adapter in between the two cut halves. The solid red of the adapter will attach to the wire half that still has power when the key is on. The red with green stripe wire of the adapter will attach to the other half of the wire you just cut. This way the power to the coils flows through the adapter. Ground the black wire of the adapter and hook the gray wire to the green wire of the tachometer. "
Hope it helps, good luck.

Sorry to bring old thread back

00Perf RedStang i read what you posted and looks right what i was thinkin, BUT i find this installation too http://www.ponyexpressperformance.com/tachinstall.html

So which one is right

BTW i tryin install tach with shift light in buddys 04 Mustang GT and he using AutoMeter adapter , please let me know because i have to installed today
Thanks