Starting in 1983, Ford introduced the Mustang platform to the latest and greatest upgrade over the factory 4 speed manual transmission to the T5 platform. These were classified as the ‘Non-World-Class” T5 5 speed. This application was rated as 265 lb/ft torque rating and was a well-deserved upgrade over previous years. The 1983-84 years offered the following internal gear set options- 1st-2.95, 2nd-1.94, 3rd-1.34, 4th-1.00, 5th-.73., & Reverse-2.76.
1985 then introduced the newer World-Class T5. This transmission still had the same overall power rating of 265 lb/ft but upgraded internal gearing made this a better application for the upcoming changes over to electronic fuel injection. The 1985-89 internal gear set options are as followed- 1st-3.35, 2nd-1.93, 3rd-1.29, 4th-1.00, 5th-.68, & Reverse-3.15.
Next, from 90-93 the World-Class T5 got a few internal upgrades. The power rating on these models jumped up to 300 lb/ft and also upgraded bearing races and synchro’s. Other changes also included an upgraded shifter and speedo drive gear options for easier gear correction fixes. 1990-93 internal gear set options were- 1st-3.35, 2nd-1.93, 3rd-1.26, 4th-1.00, 5th-.68, & Reverse-3.15. This 3.35 first gear was a HUGE improvement over previous models. In 93, Ford also had one other variation of the T5 that was limited to the SVT Cobra Mustang. This “Cobra Spec” option was the first of its kind to have the tapered input shaft bearing and improved front bearing retainer. They also included a new reverse gear braking system and synchro whereas previous models lacked these functions. Torque rating was bumped up to 310 lb/ft and internal gearing remained the same.
Ford added deeper bellhousings to the T-5 transmission for the 1994 and 1995 Mustang years, which helped to lengthen the input shaft. These enhancements may seem important, and they were in some cases, however the majority of them are impossible to observe without dismantling the transmission. The earlier T-5 transmissions had a yellow tooth speedometer drive, which was an easier to spot indicator. The light green speedometer drive was used on the 1990-1995 T-5s, and after Borg-Warner sold their manual transmission division, Tremec produced all of the T-5 transmissions after that.
The 1995 Mustang GTs were the last V8s with a T-5 transmission, but they were still produced with minor changes and upgrades. The most significant changes were needed to fit the T-5 transmission into the S197 Mustang. This means that if you're upgrading or replacing a transmission in an S197 Mustang, you'll need to pay close attention to how the transmission is bolted to the body and how the shifter is set up. The 2005-10 internal gear set options are as followed- 1st-3.75, 2nd-2.19, 3rd-1.41, 4th-1.00, 5th-.72, & Reverse-3.31.