The temp gauge doesn't work in my 94 F-150 (5.8L). I wanted to make sure the temp sending unit was connected... but, can't find it??? I looked at the front of the lower intake in the area of the distributor and I'll be danged if it's not there. Now, there is what looks like an empty boss where the radiator hose connects at the front of the intake but if the sending unit was completely gone, wouldn't it be spitting coolant from that hole?

 

Intake manifold, behind the thermostat housing..

 

It is on the left side of the engine behind the dist. The one behind the t-stat housing is the one for the PCM, they are different.