The ribs are there to prevent flashover. At one time the original equip. plugs didn't have the lines. Evadently they are decorative. The old Delco batteries didn't have the raised letters or the caps painted yellow on the original equipment bats.
George


They say money can't buy happiness. It can buy old Chevy trucks though. Same thing.
1972 Chevy c10 Cheyenne Super
In the Gallery Forum