Classic/Antique Car Repair: fuel sending unit ohms, jaguar mark, gauge wire

Question
I'm installing newer gauges in a 1956 Jaguar Mark XII and I need to know the ohms of the sending units before ordering the new gauges.

Answer
Hi Bill,
I take it you mean a 56 Mk VII. I have a Mk VII factory service manual but it fails to quote the ohms value from empty to full of the sending unit. I also take it that you are trying to purchase an aftermarket universal gauge and that is why you need the ohms value?
I don't have any Mk VII sending units or I would be glad to check their values for you.
If you can't find anyone with a sending unit to test, you could drain one tank and check the ohm value at the gauge wire (with the tank selector switch on that tank)
Either tank unit would do as I am sure both use the same sending unit. Then fill that tank and check it again to get the range.
If the sending units are frozen (rusted) you will have to go in the trunk (boot) and remove the spare tire and bracket and side panel and after draining that tank remove the six screws retaining the sending unit and remove it to see if it can be repaired. The same thing happens to the later XJ-6 ser III cars and I found that only about 50% of the ones I tried to repair could be repaired as they were prone to rusting solid.
Good luck, and sorry I can't find any ohm values for you.
Howard