+/- change

[rotorwrench]

Some ammeters have terminals and some just put the power wire through the loop on the back (inductive meters). The solution is pretty much the same either way. Change the direction of the wire through the loop or swap terminal connections as applicable.

Radios may or may not be polarity sensitive depending on how the radio gets it's internal voltage changes for amplification. The old vibrators work either way but the solid state types don't.

The ignition coil is polarity sensitive as well. I don't think the King Seeley indicators care one way or the other.