the temp gauge connects to the temp sender on the *bottom* of the engine.
the sender is mounted on a round metal plate, also called the "Taco Plate" (for obvious reasons).
the sender on top of the engine is for the oil-pressure idiot light, if it is right next to the dizzy ...
a picture of the top of your engine would help with identifying that one ...
do a search here for "Taco Plate" and you should come up with quite a few threads about the oil-temp sender location etc.
Andy