The fifth, or overdrive gear, was placed in the four-speed gearbox in the extension (or tail shaft) housing.
This made production easier and cheaper; however, it effectively limited torque capacity to around 200 lb.
The Type 9 is a popular choice for five-speed conversions of older Ford cars, such as the Cortina and RWD Escorts, and also for kit car builders since it comes with a separate bell housing which can be easily swapped around.
Overall, the Type 9 is suited for vehicles with lower power and lighter weight.
However, in applications that require more power, the Type 9 is frequently replaced with the stronger Borg-Warner T-5 transmission.