[RCW]

Your question has me baffled. Am I to understand that you need an adaptor to connect the thermal bulb on a mechanical temperature gauge to the hole in the engine head?

If so, you do not want anything that will extend the fitting outside the head, as the bulb must be immersed in the coolant and not up in some extension.

If you simply need an adaptor, take the electric sensor to an auto parts store with the new line and bulb, and get a ring adaptor that keeps the bulb inserted at the same level as the OEM sensor. If the bulb is not fully immersed your temperature readings will not be accurate.

Now for my real question. Why switch from an electronic gauge and sensor to a mechanical unit? The engine is rubber mounted and you will have to use at least two full 6" wraps of the tube located somewhere near the head to avoid cracking the tube from vibration.