Will the stock water temp sensor for factory guages work on a aftermarket temp gauage? I plan on installing the console gauge pod someday but in the shorterm I plan on useing a inexpensive 3 gauge unit. The car is a 69 with a 350 crate motor.

Clint

Probaly not, use the sensor for the gague

As John said, the gauge and it's sensor go together. Sensors have a wide range of resistance differences. Some sensors make more resistance with increasing temperature (Positive Temperature Coefficient) while others decrease their resistance with temperature (Negative Temperature Coefficient).

shorterm I plan on useing a inexpensive 3 gauge unit.
you can try it in a jug of water and temp gauge.
It may read 'wrong' but if u know where 180, 212 deg is on the gauge then are ok.

As said, GM uses the negative temp coefficent meaning cold, high resistance, 5K to 10 kohms, read from the terminal to sender body; sender at operating temperature, low resistance, approximately 150-180 ohms to indicate 180° on GM gauge, maybe, but close.