Not Amps...
Milliamps. And I don't have the dope your looking for.
Gauges work with small current variations, producing a magnetic field, indicating zero to full scale.
Resistance values of senders in ohms typically 0 to 60 and could go as high to 500 with some designs.
There are two types of electrical gauges in the Humv. Moving coil (voltmeter) and the double coil (oil, temp, pressure).
Here's a print to show connections to the double coil.
Gauges and senders are purpose matched to work together as to track small resistance values indicating calibrated oil, temp, pressure readouts.
The Voltmeter is sensitive to change (as required) and is a characteristics of moving coil designs.
Double coil meter / gauge advantage are insensitive to voltage variations by design, providing accurate readings over a fluctuating supply voltages as in a HumV.
Could be a bit of experimenting to "dial in" your results.
How about a military universal "glass panel" cluster with configurable layout, speedo and tach, any gauge you could ever think of, all at the same time, blue tooth enabled, plug and play ???
The MO U know to GO, CAMO