Temp Guage issues

You probably have a bad "voltage limiter." The original limiters pulse like a flasther unit. The reason the gauge needles don't "pulse" is because they are slow to react. So with the key on in "run" you should have battery on one terminal, and a pulsing action on the other. If you have an aftermarket limiter with a solid-state regulator installed, you should be showing around 5 - 5.5 volts.

I think Redfish here sells replacement units, and you can "roll your own" with some parts from Radio Sh$$

One approach:

http://www.forabodiesonly.com/mopar/showthread.php?t=75065

another:

http://1962to1965mopar.ornocar.org/ml-instrument-voltage-regulator64.html