robert giles,

A '55/2 sending unit should be a 30 ohm unit. I believe your resistance measurement would be 30 ohms with the float at FULL and 0 ohms with the float dropped all the way down to simulate EMPTY. I could very easily have this bass-ackwards, but a quick test with your ohmmeter will tell the tale. Any midpoint reading will be somewhere between 0 and 30 ohms!

It sounds like this might be too vague for you. If you get the 0 and 30 ohm readings, the little wire wound resistor is contiguous and should read properly at any fuel level.

Stuart