Differences Between the C6 and AOD

by Brett Thorne
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The C6 transmission is a three-speed that appeared in most Ford trucks between 1960 and 1997. Ford stopped using the C6 in most of its trucks, but the transmission is still commonly used in drag racers today. The AOD transmission was introduced in Ford automobiles in 1985 and eventually replaced the C4 and C6 transmissions. The AOD has an overdrive gear and was updated in 1994 with electronic controls and re-christened the AODE.

Transmission Types

The C6 is a non-electronic, three-speed transmission. The AOD features a four-speed, non-electronic transmission. It was not until 1992 that Ford introduced the electronic version of the AOD, the AODE.


The C6 was included in nearly every truck Ford manufactured between 1960 and 1997. It was also included in the F-Series of Bronco manufactured between 1980 and 1991 and the F2, F3 and F450 models manufactured between 1992 and 1997. The AOD was used in the Bronco F Series manufactured between 1985 and 1993.

Engines and Gear Ratios

The C6 was included in the following engines: 300, 302, 351w, 400, 351c, 351m, 460, 6.9L, 7.3L, 352, 360 and 390. The AOD was only offered in the 300 and 302. The gear ratios for the C6 are: first -- 2.46:1, second -- 1.46:1 and third -- 1.00:1. For the AOD, the gear ratios are: first -- 2.40:1, second -- 1.47:1, third -- 1.00:1 and fourth -- 0.67:1.

Trans Codes and Mileage

The trans code on Fords helps owners understand exactly what is under the hood of their car. Ford Motors has produced at least a dozen different types of transmissions, and the trans code helps owners decode which type of transmission their car has. The trans code for the C6 is "K" and for the AOD is "T." Because the C6 is capable of handling more power, it requires more power so the fuel mileage tends to suffer in trucks running the C6. The AOD typically offers better mileage.

Appearance in the Instrument Panel

Ford trucks that came with the C6 transmission have the following shifting appearance: P R N D 2 1. The AOD models are: P R N (D) D 1.

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