[rotorwrench]

Using voltage to describe the coil is somewhat problematic in this day and age since most counter people haven't been around long enough to know what they are.

The can type coils with the 1.5 Ohm primary coil winding can be used for 6 or 12 volt but a 1.3 to 1.5 Ohm ballast resistor has to be utilized when running them on 12-volt. Coils with 3-ohm primary windings may or may not have a "12V" marking on the outer case. The 3-Ohm coils need no ballast on 12-volt systems.

The key question to ask is "what is the resistance value of the primary". That doesn't mean any counter people will know that though so it's up to us to look for the specs or ask some one who will do that for you,