Since small block V8 cylinder heads are interchangeable from side to side, the coolant port at the back of the head dead ends into a passageway in the intake manifold. By drilling and tapping the manifold for a pipe thread, a temp sensor can be installed back beside the distributor on the driver's side of the engine which will give a more accurate picture of actual coolant temp than one in the thermostat housing. We used that method to monitor coolant temp on the race engines for many years.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!