One new old stock original Smiths brand fuel gauge (made in the U.K.), part number BF2200/05 or factory # C22372.  This fits:

Jaguar MKX 3.8L 07/1963 - 1964

It is very important to check the part number on your old gauge and compare to the part number being sold.  You will find the part number on the gauge face or under the pointer shield.  If you require a different part number please feel free to drop us an email with the required part number.