
Yes, its too big. Yes, I can only utilize half of it. Yes, the shift light is overkill. But it brings me joy.
ANYWAYS! I connected the tach to the TACH out put of the EDIS module. The same one I used on the Equus unit without issue. The Autometer unit did not want to play nice. At first I though I had a bad unit. After hours of testing with a DSO and reading internet stuff I decided to try a different approach.
If you are using an Autometer tach with a Ford EDIS ignition system you can use the PIP circuit (see diagram below) or tap MS 2 pin #24 for a tach signal. This circuit produces a clean 5V square wave. Even though Autometer advises against using a 5V signal it seems to work just fine.

I hope this helps someone in the future. Happy Motoring!
-Nick-