The schematic diagram makes dotted-line reference to an "Extra Ball Conversion Kit" at locations B-10, G-10, and G-20. This option is not mentioned in the manufacturer�s flyer nor in the German-language documentation shown here. We did not find obvious reference to it in the Williams 1966, 1969, or 1971-72 Parts Catalogs. See Williams' 1970 'Gay 90's' for pictures of what this kit may look like for Big Chief. If anyone has pictures of this kit installed in a Big Chief, please contact us. If anyone has an Instruction Manual for this game, please contact us.