Raoul,
It is best to state what you are working with. Many people have information in their "signature" but they ask questions about other projects (trucks, engines, etc).
What year engine? 216 (6v, originally)
What year gauges? 1951 (6v, originally)
6v or 12v electrical system? (12v, now)
If you do not know, people will post ways to determine this.
Fuel gauge - is voltage sensitive. If it is 6v and used with 12v it will most likely stop working. 6v and 12v reproduction gauges might be available. If it has been fried, it is not repairable.
Temperature gauge - mechanical sender until mid-50s and then electric sender. The sender hole got larger when changed to electrical - an adapter for the older mechanical tube is available.
If you are missing your sender tube, your need either a new tube and/or a new gauge unit (I think a broken or missing mechanical sender tubes means you need a new gauge - someone will clarify/correct).
