You should not. They are calibrated for 73 ohms to 10 ohms full to empty. The only thing is, if you have a replacement sending unit, it will not be linear. The first 1/2 tank or more will drop quickly on the gauge because of the indent in the tank for the spare tire well. Apparently you can get devices to fox this, but I don't worry about it. I know that's how it reads, so I take that into account.
Cley