[Lynn Eades]

Stephen, there are basically two types of senders. one type is an on off switch, that turns on (or off) a light. (these are generally the small ones.
The other sort has a diaphragm in it to send a varied signal (resistance) to the gauge.
This is what you require. My understanding is that Ford used two different units, The later one that Michael shows (# 80, suits a 0 to 80 psi range) and the earlier one (#50,which suits a 0 to 50 psi gauge) Which is probably what the C01UC-9278-B is.
If you have an old one, it will probably work. It can be tested if the ignition is on, with the wire disconnected from the sender, the needle should move to one end of the scale, and with the wire grounded on the engine block (earthed) the needle should travel to the other end of the scale. If you get this result, the gauge is o.k.
My understanding is that the senders work with a 6 or 12 volt system, however the gauge unit requires the fitting of a resistor to convert it from 6 to 12 volt.
I am confused on this because I have see senders marked "12 volt".
If you use the wrong sender, the gauge will read incorrectly. You would be able to buy a modern sender to match closely your gauge unit. You may also need an adapter to fit it to the engine.