Coil wiring stock 6 volt

[rotorwrench]

If you ever find a can type coil from the late 40s early 50s, they will generally be marked Dist & Bat on the terminals so it doesn't get confusing but that changed after 1956 when everything went 12-volt negative ground.

You can still get the little coil polarity testers from a lot of early parts sources but you can also use a pencil to check it. Although they will function either way, an ignition coil is only at peak effeciency when polarity is correct. You never know whether the manufacturer got the + or - in the right places either these days. Anyone who believes that polarity doesn't matter needs to get more education than what they had before a statement like that.