Originally Posted by Scndsin

Here is the temp sending unit installed with the probe on the output side of the thermostat housing. If you take a look at your housing there is a pad/boss cast into it where in the 70s/80s there was a themostatically controled vacuum valve. (I've got one off a 73-302 in a junk box, but its pretty rotted) At any rate I drilled it & tapped it for 1/2inch pipe thread to accept the supplied fittings of the mechanical temp sending unit. Bear in mind that the support arch on the nose of the thermostat has to be installed horizontally rather than vertical cause the probe sticks down far enough to interfere with the thermostat if installed vertically.