Sending unit ohms?

I have a '53 M38a1 with (I think), a mid 70's CJ-5 15 gallon gas tank. The previous owner told me that the reason the gas guage doesn't work is because the ohms on the tank sending unit doesn't match the gas gauge. So, would it be easier to replace the gauge to match the sending unit, and if so, what are the ohms of my sending unit, or would it be easier to drop the tank and match the unit to the gas gauge? I have aftermarket gauges in my M38-a1, but they were made specific for A1's with 12 volt conversion.

Any advice?

Dondo