What automatic Transmission for a 390FE?

[Mark IV]

Originally Posted by Goober

Joey, the C6 is probalby what was in the TBird you pulled the motor out of. The lesser transmission was the C4. The C6 was always put behind the big blocks. If fact, Shelby put the C6 behind the twin turbo Cobra that sold at BJ last year. Cast Iron and can handle anything you throw at it. Depending on your 390 build, say 450 safe HP, a stock C6 or a slighty uprated C4 will take all the torque you give it with your motor.

Mark

Actually, not. The first C6 in a Thunderbird was 1966 and it was used on the 428 and also randomly on the 390s in 66. The trans used on 'Birds from 58 to 66 was the medium-case MX (Not the FMX and NOT the C4). The 427 twin-Paxton Cobras used a large-case MX from a Lincoln 430/462 powertrain.

The MX series came in three flavors, small, medium and large case which is a description of the cast iron center case length. I have the lengths around in notes someplace and will post them. The MX series was revised in 1961 with the addition of a vacuum modulator for shift improvement. C6's have integrel bellhousings and are all aluminum, MX's have cast iron centers, aluminum tailpieces and alloy or cast iron bellhousings dependant upon original application.