Original Parts with an Original Fit!

Ford Mustang Top Loader 4 speed Manual Transmission

The Ford heavy duty top loader 4 speed transmissions were, and may still be, the toughest and most reliable manual transmissions ever built.

How have they changed over the years?

The early (1963, 1964) top loaders had a small input shaft with 10 splines and a 15/16″ diameter.  The output shaft on these early transmissions had 25 splines.

In 1965, these early 4 speeds were upgraded to a 28 spline output, while the input remained the same.

During the 1967-1968 era, Ford had to come up with a strong, bullet-proof 4 speed for NASCAR competition.  This became the NASCAR Big Block 4 speed transmission and it had an input shaft with a 1 3/8″ diameter and a 31 spline output shaft.  A select few of these transmissions were used in NASCAR grand national racing.

The NASCAR transmission was also used in 1969 and 1970 Boss 429 cars.


  1. October 15, 2009    

    looking for top loader 4 spd. for mustang maybe cougar any help appreciated, thanks mark

    • October 16, 2009    

      Hi Mark, We do have a Top Loader 4 speed, as well as other parts. Contact us for details.