Here is some info on trannys I ripped off from another site.
In past 35 years Ford has produced many different rear-wheel-drive automatic transmissions, most of which have been introduced since 1980. The following list outlines a brief chronology of Ford Motor Company’s modern automatic transmissions followed by descriptions of some of the more complicated members.
The FMX/Cruise-O-Matic three speed evolved from the 1950’s Ford-O-Matic and was used until 1980 when the AOD was introduced.
In 1964, the C-4 was introduced, providing a lightweight and durable three-speed automatic which is a favorite among racers today. The C-4 was produced until 1982, when it was replaced by the C-5.
The C-6 appeared in 1966 as a heavy-duty unit primarily used behind big-block engines or in large vehicles. Internally, it is much like a scaled-up C-4. The C-6 is still used today in certain truck applications.
The French-built C-3 was first used in 1974 in the Ford Pinto and remained until the Merkur XR4TI was dropped in 1989.
The Automatic Overdrive (AOD) transmission was introduced in 1980 as Ford's first four-speed automatic overdrive transmission (a.k.a. AOT or FIOD in some literature). Internals are loosely based on the FMX. The AOD was finally replaced by the AOD-E/4R70W in 1994 for all remaining applications.
1982 brought the C-5 which was essentially a stronger C-4 with a centrifugal torque converter lock-up clutch and an enhanced valve body for smoother shifting. It was produced through 1986 and was completely replaced by the AOD.
The A4LD four speed overdrive transmission was introduced in the 1985 Bronco II/Ranger and saw use behind many 4 and 6 cylinder engines until the 1995 model year when it was replaced by the 4R44E and 4R55E electronic transmissions. The A4LD was the first Ford transmission to use an EEC-controlled torque converter lock-up clutch and later became the first to use electronic shift control (via a 3-4 shift solenoid). The French-built A4LD was created by adding overdrive to the front of the C-3 three-speed unit.
Full-size trucks first received the huge E4OD (Electronic 4 speed OverDrive) transmission in 1989. Internally, it is essentially a C-6 with overdrive added to the front (such as the A4LD is to the C-3) and an EEC controlled valve body.
The AOD-E transmission first appeared behind the 4.6L modular V-8 engines in 1992. Essentially a beefed-up electronically-controlled version of the AOD, the AOD-E also includes a new and stronger wide ratio model (the AOD-EW or 4R70W) which was introduced in the 1993 Lincoln Mark VIII. The AOD-E (in both standard and wide ratio versions) completely replaced the old AOD in 1994 with a new case that mates to the 5.0L and 3.8L engines.
For 1995, the 4R44E (4 cyl. - light-duty) and 4R55E (6 cyl. - heavy-duty; i.e. Explorer) electronically controlled transmission replaced the A4LD. It is mechanically identical to the A4LD.
Later, the 5R55E was introduced behind the 4.0L SOHC V6 as the first domestic five-speed automatic. Mechanically similar to the 4R55E, the 5R55E uses revised controls to leverage the mechanical capabilities of the 4R55E to deliver a fifth forward speed.
