Tranny Choices
Sweet and simple is all one can say about this option list. A three-speed manual was the base transmission for those who didn't need a granny-low First gear. Fortunately, this wasn't offered on the F-100 series with a single-speed transfer case, as this tranny and high axle gears would have relegated this combo to very light 'wheeling. But the true truck tranny was the NP435, a heavy-duty four-speed with a 6.69 First gear, the most popular option throughout this series. The cast-iron-cased tranny is easily identifiable by the aluminum top shifter housing, as opposed to the cast-iron top of the T18 style. In 1975 the C6 automatic transmission was introduced--it was a truly tough unit that was fitted to both full-time and part-time 'cases. The C6 is strong enough to handle any engine swap, but different bellhousing patterns were used between big-block and small-block V-8s, with a weird one or two thrown in for good measure.
Differentials
The ½-ton Ford pickup is best known for its rear axle, the ever popular 9-inch. This integral-carrier-style diff was introduced back in the late-'50s and was the mainstay of the light-truck line. The extra pinion bearing support and dropout centersection made the unit super strong yet simple to work on. But for owners who needed something stronger, the Dana 60-2 flanged rear axle was an option for the F-100 from 1967 to 1969, although some may have been found in later-model trucks. The front axles were the standard Dana 44-F with the differential on the driver side. The F-100/F-150 coil-sprung front suspension was alone in the 4x4 arena.
The heavier F-250 received a full-floating Dana 60 rear and 44-F front end for standard duty. But again an optional Dana 60 front was available in the heavy-duty rating and the crew cab model. But the toughest truck that Ford produced was the F-350, with a 60 front and 70 rear as standard equipment. Of particular interest are the reverse rotation front Dana 44 and 60 axles that have the pinion shaft entering the housing above the axle centerline, which allows a better driveline angle and a lowered-vehicle silhouette for easy entry.