The intakes I have now have a boss and a threaded hole in the intake manifold's coolant runner between the thermostat and the driver's side head. This is for a mechanical temp gauge; there is also a smaller threaded hole on the passenger side for the factory electronic temp gauge. However, I've had a couple of intakes in the past (early seventies) that had only the passenger side provision for the factory electronic gauge, and no built-in provision for a temp sensor for an aftermarket mechanical temp gauge. What I did was drill a hole in the driver's side coolant passage (between the thermostat and the driver's side head), then tapped the hole for the sensor fitting. The manifold casting was thin there, so I put a couple of washers under the adapter and screwed the adapter into the intake after coating it and the washers with JB weld. Looked OK and lasted until I switched intakes years later (back when the car was still a daily driver). At the time, no one offered a spacer like the one illustrated above. So today, you can do what I did back in the day for almost no money, or you could go fancy and use the spacer under the thermostat housing as illustrated above. :thumbsup:
