I'm sending out some dead gauges to be converted from the 5V regulated style to modern 12V. The new fuel level gauge can work with stock fuel senders, it simply needs to be calibrated to the resistance range of the sender. So I'm faced with two options.

First, use an original sender, and find out what resistance range it operates on. I've tried to measure mine, which is really flakey, and seem to get about 3-80 Ohms. Can anyone confirm that this is the normal range, or is mine to far gone to give me the right values? I want to make sure I have the right values so the gauge is calibrated properly, and I can't seem to find that information printed anywhere.

Second option is to buy a new, cheaper fuel sender with whatever resistance range I want. It's the perfect opportunity since the gauge will be calibrated to whatever I use. Does anyone know of a 3rd party sender that fits and works in these cars?