This set of 6 Motorcraft AG42C spark plugs is the perfect replacement for your I6 AMC or I6 SB Mopar engine. These non-resistor plugs are made of copper and have a thread diameter of 14 mm and hex size of 21 mm. They have a voltage of 12 V and an installation depth of 19 mm. The spark plugs come with interchange part numbers STK54, AC4, BP5EA, 38, and 65, and OE/OEM part numbers 5613522, 98079-55841, 2098360, and 98079-55854, making them a versatile option. These spark plugs are standard configuration and are not considered vintage parts. They are compatible with gasoline fuel type and are made in the United States.