Black rubber fuel line hose diameter
 

1985 300D turbo.
Does anyone know the correct ID in mm for the black rubber fuel line hoses both attached to the fuel tank and in the engine compartment going to the primary filter? A google search shows that some are using 5/16 inch ID with a SAE 30R7 rating. The Mercedes EPC shows a Mercedes part number but doesn't disclose the size. Since I need to buy hose, I might as well try to get it in the mm size as it would probably be slightly different in actual size and true to the designed diameter.