The redesigned C-Series International trucks of 1961 were far more evolutionary than revolutionary; however, the models came off as a new design. While the C-Series cab dated to the A-Series of 1957, it was situated approximately six inches below the old floor line. This modification removed the integral step inside the door, but also make a lower, sleeker profile (or at least as sleek as practical for a working truck). The skirting at the bottom of the styled Bonus Load pickup box was also lowered to match, but was markedly less of a change than the cab.

Annual model year changes weren’t the norm during this time for International Harvester, which tended to focus on integrating minor running changes as needed, with specific changes oriented towards the end of the calendar year. For 1961 and 1962, the Light Line ranged from the ½-ton C-100 through the 1-ton C-130. From 1963 through 1964, naming changed to the C-900 through C-1300. The 1965 run saw the Light Line renamed to the D-series, ranging from the D-1000 through D-1300. A year later they became the A-Series, from the 1000A to the 1300A. Similarly, 1967 trucks were renamed the B-Series, with the 1968 model year trucks returning to the C-Series moniker of the 1000C through 1300C models. Despite styling revisions like more side trim and squared off grilles, International’s trucks now looked very dated compared to the competition.

With smaller van-based pickups from Ford and Chevy, IH designers figured they had to compete with a smaller pickup of their own. Introduced in 1964, the C-900 had a unique 6-foot stepside box and was the only Light Line pickup to use the 152-cid slant-four engine from the Scout. The engine was deeply geared to compensate for its lackluster 93 horsepower in a full-sized pickup, which made it work far too hard to see much economy from the truck on the highway. Even so, they were popular enough to warrant limited production through 1968, although by then the trucks came with a standard 266-cid V-8 and the 6-foot Bonus Load full-width box.