Hello Tim,
I have 2 G2X units: 1 black box, 1 red box.

I have the black box set up using the MSD MGR Ignition Pickup (MSD 8918).
Used on an SAE student design, Briggs motor with magneto ignition. Everything works fine.

The Red Box, I am stilling up the same, just another SAE vehicle, same motor.
I cannot get the MSD GMR to work. I am now on my 2nd GMR.
The black box GMR that works, it measures ~ 180 ohms across the leads and signal wires.
The 1st GMR on the red box, measure nothing across the leads, only testing the sensor itself.
The 2nd GMR that I bought to replace the first, that read ~80 ohms across the leads.
I tested the 2nd GMR setup last night, and still cannot get a tach reading.
When I setup the black box unit right next red box, and put the GMR pickup on the ignition,
on the same motor, the black box tach will register, but the red box will not.

I am already into the red box for the cost of 2 GMR sensors now, and still cannot get this to work.

please help?

ps - good to finally meeting you and thank you at PRI