1941 K1 questions

[McDarrunt]

Were the K series pickups positive or negative ground? I got a 41 half ton that has after market gauges but found a very clean original instrument cluster so want to make sure to wire it correctly. The present set up has an internal regulator alternator and 12v negative ground. I can use voltage reducers on the gauges but wonder about a source for the original sending units for temp, fuel, and oil. Thank you for any direction; Evan

[48international]

They were positive ground