Engine Temp' Sender

Yeah theres an aftermarket temp, vacuum, oil pressure and voltage gauges under the dash. The temp gauge doesnt work there either, i think the PO had put another temp sender in the top radiator hose. So it shouldnt give a reading until the thermostat opens right??

I want to try and link up the original water temp sender to the aftermarket gauge to see if it will work.
After reading previous posts it appears the voltage regulator may have gone behind the dash as the original Fuel gauge and Temp Gauge dont work at all!!!

Are the voltage regulators still available??
Also are the stock gauges still available??

I appreciate your help greatly.

Nick