Which Transmission is Right for Your Fox Body?

It's not hard to set up an engine that makes significantly more power than your Fox body was built with, and that puts a serious strain on the drivetrain. Fortunately, there are several transmission options that can handle the most radical builds from rebuilt stock units to complete aftermarket gearboxes.

T5 

This Borg Warner transmission was used in all Fox bodies from 1983 onward. It has 5 forward gears and an unsynchronized reverse. The version used with the 2.3 liter has weaker syncros and different gearing than the one fitted to the 5.0. In stock form, the 2.3l version is rated at a maximum 240 ft-lbs. of torque, 86-89 5.0 transmissions at 265 ft-lbs, and 90-93 5.0 transmissions, which use stronger gears and revised syncros, at 300 ft-lbs. A “Cobra Spec” version offered in '93 Mustang Cobra is rated at 310 ft-lbs. These transmissions have some minor refinements over earlier versions including the use of needle bearings on some output shaft gears for decreased drag.

This transmission was used in production vehicles for 30 years in everything from AMC Spirits to the 2010 V6 Mustangs, which means there's a wide range of gear options and parts available. A heavy-duty version is available from Ford Racing, while Tremec, the company that bought Borg Warner's manual transmission division, still makes the standard T5.

A4LD 

This automatic was used in four cylinder Mustangs as well as Rangers, Bronco II's and Explorers. Although basically a C3 with an added overdrive, it's a fairly weak transmission, especially in the form used with the 2.3l. Better versions were introduced in the 1990s, but its limitations make it inferior to other transmissions that will easily fit in the Fox body.

AOD 

The automatic used in 5.0 Mustangs, this transmission was notorious for issues with the overdrive gear, causing the transmission to hunt between third and fourth on the highway. Over time, development of this transmission cured this issue, while robust components borrowed from the FMX transmission used with older big blog Fords make this a great starting point for a performance-oriented build.

Looking to swap a Coyote into your Fox body? Performance Automatic makes a high strength AOD specifically for this application with the right bellhousing as well as a wiring harness and computer.

C4

This three-speed replaced Ford's first automatic, the Ford-O-Matic, back in 1964. It was paired with larger straight 6's and small block V8's like the 302 the 5.0 is based on. Early versions were designed with the option of staying in second gear. This was changed to a D-2-1 shifter in 1967. Improvements were made in 1970, increasing internal strength and reliability. A lockup torque converter was added in the early 80s, creating the C5. Despite this improvement, C5s are weaker than C4s.

The C4 has a reputation for unfailing reliability and a simple design that can be rebuilt without the need for special tools, making it a perennial favorite of drag racers. A 1970 or later transmission fitted with a high stall speed torque converter is a good choice for racing, but donor transmissions are becoming harder to come by. Fortunately, there are several relatively inexpensive aftermarket options that have upgraded components to handle far more power than the stock unit.

Unlike the other transmissions on this list, a C4 was never used in the Fox body. To get this gearbox to fit, the transmission crossmember needs to be repositioned. 

Where Do I Start?

www.andersonfordmotorsport.com carries everything you need to get the best performance from your Mustang including high performance transmissions. We've been helping our customers built Fox bodies since they were still being manufactured.