OK, installed a new temp sending unit and will add the fluid on Monday (the temp housing was leaking so I re-tapped the holes and installed the correct length bolts from the PO as well as cleaning up the housing/intake).
I do also want to install a mechanical gauge.
Question (just to be sure), the mechanical gauge goes here, correct (pic below).
After I get it completed I will fire it up and see if both gauges work, if not then I will continue to trace it down.