Dash Gauges

[71MoneyPit]

hey everybody,

finally getting the Money Pit all finished up, but im having a problem getting the gauges to work with the caddy. What I am wondering is if any of you know where the sending unit for the water temp is and where the sending unit for the oil pressure is. There is one right above the front spark plug on the pass. side cyl head, and another one in the back of the driver cyl. head. and there is also one right on the front of the engine that is threaded in right below the intake. I have no idea which ones im supposed to use or if they will even work with the trucks gauges

Also, can't I just thread a fitting in where the oil pressure sending unit is and hook that up to the mech. gauge in the dash

And one more thing, what would be making my fuel gauge read empty when it is at least half full

thanks in advance