For the Walbro 255, Bosch 040, etc. fuel pump conversion the correct rating for in-tank fuel hose is SAE 30R10. NAPA sells hose in the correct diameter for OG 9-3's (and probably others), 5/16" (7.93 mm). Part number NBHH209 for 1 ft. It's not cheap. Gates Literature: Avoid Comebacks...