OEM M97938 master cylinder brakes is a cast iron brake master cylinder. The bore diameter of this one is 1-5/16" equal to 33.344mm. With two outlet ports of 1/2-20" for primary port & 9/16-118" for secondary port, the brake mster cylinder will be workable in 1983 1 Ton C-Series Pickup, 1984-87 1 Ton C-Series Pickup, 1983 1 Ton K-Series Pickup, 1984-87 1 Ton K-Series Pickup, 1987-91 1 Ton R-Series Pickup, 1987-91 1 Ton V-Series Pickup, Ford E-350 1977-1983 & F-350 1977-1979. There are other reference number as follows: MC39435 D7TZ2140A 14066425
