The standard engine for the early ’59 Travelalls was the legendary 240ci IH Black Diamond six. Its ancestors had debuted in the ’30s as one of the earliest overhead-valve truck engines. For 1959, it was still fresh from several upgrades, including a redesigned canted-valve head and full-flow oil filtration. There were three similar six-cylinder engines this year, the 220ci, which was a short stroke version of the 240ci offered only in the economy 4x2 A-100s that made 113hp, and the optional 264ci, which had a slightly longer stroke and a healthy increase in the bore size. The 264ci made 155hp, about the same as the 266ci V-8. The V-8 that was optional early in 1959, but became the standard engine by late in the year. Both the sixes were available as LPG models.