I've acquired an older Warner trailer brake controller. It looks like it's from the 40s-50s vintage. I compared the inside of it from a later warner trailer brake controller and the contacting "fingers" look thicker on the later one. By look at just this difference I was wondering if this would make that older controller a 6-volt? If so, will it hurt anything if I ran 12-volts through it to control the brakes on a 2-axle trailer?
