Jim Smart
June 22, 2015

One of the most popular drivetrain mods done to early Mustangs is to swap out the non-overdriven three- and four-speed transmissions with the later-model overdrive T-5 five-speed. Not only does the T-5 provide a highway-friendly overdrive, but it also provides a deep First gear ratio for better off-the-line performance. The Mustang’s T-5 five-speed transmission has been in continuous production for 34 years. Originally designed and manufactured by Borg-Warner and first offered in the Mustang in 1983, the venerable T-5 has been a Pony Car mainstay for longer than a lot of us have been licensed drivers. The fully synchronized T-5 transmission is a countershaft-style helical gear unit. In the late ’90s, Borg-Warner sold its manual transmission division to Tremec, which is still building new T-5 transmissions to this day—they are available from Modern Driveline along with all of the parts necessary to service them.

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