The Stovebolt Site Forums The Parking Lot Big Bolts Biggest 6-Cylinder Engine?

I don't know if it's the same engine as crenwelge has mentioned, but i'm looking at a catalog titled, "GMC Heavy Duty Trucks- Gasoline-diesel", published 5/1949 that list a group of engines as new for 1950, & they are a 318, 360, 426, 503, & 707.