I'm trying to install a little 3" tachometer but I can't seem find the correct wire coming from the coil or distributor.
I know my green wire off the tach is the "signal wire" but when I go searching for a green or brown wire under the hood I'm not finding it.

1990 GMC C1500 \ 5.7L 350

Here's a shot of the distr. and I'll get one of the coil tomorrow when the sun is out.
Any help greatly appreciated.

The distributor has a connector labeled ABCD on top, just FYI.
Thank you.