Coolant Temp Gauge Help Sought

[Stepside 67]

Hi all. I am trying to get the coolant temp gauge to work on my '67 C10. I bought the full gauge cluster from Classic Industries and am struggling to get the completion of all instrumentation wrapped up. Absolutely no instructions came with the cluster I've called them a couple times and each time they say they'll check with their tech group or the supplier and call me back but have not done so.

So far, I've switched the wires in the cluster connector (going from idiot lights to gauges) as per instructions I found here. I have continuity from one end of the green wire to the other. I have tried two different senders. The needle seems to blip a tiny bit at start up, but won't register any temperature.

Please see the attached photo that I took of the rear side of the gauge. Do I need a separate ground wire to one of the studs? If yes, which one?





Any other advice as to what I need to do to get this monkey off my back will be VERY APPRECIATED.

Thanks!