Fuel gauge help???

I have an Aero tank I took out of my 89' and put in my 98' XJ. It all fits fine, but not sure what to do about the gauge? The tank has a sending unit with a single wire, and the 98' uses a two wire setup. I tried to use to use one of ether of the wires, and got nothing at the gauge. What do I do, is there another "universal" sending unit that uses two wires or is there someway to use what is there? Should one of the wires have power or ground going to it?

Please help with any sugestions, I don't want to hang another gauge off the dash. (unless it's the only way)

So nobody has any advice here or where I might be able to find somthing.

I can't be the only person that has tried to put a larger tank in a 97+ XJ can I?