[Fulltiming]

I was on the phone with Don Bradner looking at images of the 555 and the 903. Based on the valve cover, he concluded the engine shown above is a 555. Three items lead us both to that conclusion: 1) vitrually all, if not all, 903's had a raised 903 stamped in the valve cover near the top, 2) the decal on the valve cover is longer and not as tall on the 903, and 3) the valve cover for the 903 has a split horizontal line below the cover bolt that then continues straight down on the ends rather than having the lip that the 555 has at the bottom of the valve cover.