The BD 240 of 1957 was the latest in a long line of stout IH sixes. IH had debuted an OHV six in the ’30s, when most manufacturers were still using flathead, valve-in-block powerplants. In 1957, the engine got a major cylinder head revision that resulted in a 10hp and 18 lb-ft power increase. IH gave their engines a Diamond moniker and engine paint to match. The Silver Diamond was the original light truck OHV engine introduced in 1949 and came in an argent color. A Green Diamond L-head engine preceded it. The Black Diamond replaced the Silver starting in about 1955, but there were also Blue-Grey Diamond engines, Blue Diamond, and Red Diamond, the latter seen in the larger trucks. With only 39,000 miles, this engine didn’t need much work.