So I did a little experiment and remembered that the late nineties ford Rangers and Aerostars with the 3.0 V6 engine used a temp sender at the heater hose outlet.
Ordered one, Dorman 47993, which has 3/8 pipe threads just like the intake where the ouput for the heater is. Also has another female 3/8 pipe to install a sender.
Bought a 1/2”x12” brass tube at ACE Hardware, so it can get down into the coolant like the original, and used a 1/2 drill bit take a hair out of Id of fitting an left a shoulder at end. Going to put a little red loctite on it and push it in. The last 1/8” has to be pressed in because I used a normal 1/2” bit, which is good.

Carl
Kansas