As time rapidly moves farther and farther away from the 20th century mark, more and more customized classic truck owners have discovered an increasing desire to restore their truck's mid-century appeal with a hopped-up early V-8 engine. When it comes to an early Effie there's nothing quite like Ford's first series of OHV V-8, the venerable Y-block to satisfy the craving. Unfortunately though, if a person wants to enjoy the convenience of an automatic transmission behind their souped-up Y-block mill, the weak link in the equation is the original equipment Ford-O-Matic transmission. Although not quite as notorious as Chevrolet's cast-iron two-speed Powerglide the heavyweight cast-iron Ford-O-Matic is wrought with drawbacks typical of a first-generation automatic transmission. At the top of the list is inefficiency, or as it is referred to in technical terms: parasitic loss. Much like it sounds, the expression refers to how much horsepower is sucked up, or robbed, from the rear wheels due to the energy required to pump the transmission and overcome inherent friction.
Next in line on the list of good reasons to upgrade from the Ford-O-Matic to a Ford AOD are the benefits reaped from three decades of evolution. Introduced in 1980, the AOD isn't prone to slow upshifts when the transmission is cold like the Ford-O-Matic is famous for. For those of you unfamiliar with the malady, imagine what your concerns might be if you felt your engine was going to grenade at redline before the transmission shifted into the next range, and the R's dropped. Speaking of R's brings us to the greatest reason there is to upgrade to a modern automatic transmission, and that's the "OD" in AOD, Overdrive. With a 0.67:1 overdrive ratio, the AOD will effectively raise the 3.73:1 gear ratio most common in '53-'56 F-100s to 2.49:1, which in anyone's book is a tall set of rearend gears.
Now that we covered the Ford AOD in generic terms, lets move on to stating that not all beefed, or rebuilt automatic transmissions are created equal. That said, the AOD and the Y-block adapter we are using behind our '57 T-Bird engine is from Gearstar Performance Transmissions of Akron, Ohio.