I have a 72 240z, my temp gauge decided to stop working today, where is it located? I cannot find it in my fsm. thank you

It's located on your thermostat housing which is under the engine end of the upper radiator hose.

A lot of times it is just a poor connection between the female bullet connector and the sensor. Check the operation of your gauge by grounding the sensor wire (it should peg the gauge with the ignition ON). If that works, then try and clean the inside of the bullet connector and sensor connection. If you still don't get a reading after reconnecting the wire on the sensor then replace the sensor.

ha, had a looksie and the wire is snapped, will recrimp, thanks guys!

word of warning!!! make sure the shoulder on the temp. sender unit is the same length, just replaced old unit with "standard" unit from rock auto - the shoulder was longer and broke off the nipple from the thermostat housing!! time for a new thermostat housing.....