Ford Toploader transmission

A Toploader transmission is a manually shifted three and four speed gearbox introduced in 1964 by Ford Motor Company to replace the BorgWarner T-10. It was used in most Fords and Mercurys from 1964 until 1973 as well as some foreign models. Officially designated the 3.03 three speed or Ford design four speed, the Toploader got its name from the fact that the access plate to the inner workings was located on the top of the main case as opposed to the side, a convention used on most gearboxes such as the Ford Dagenham or GMs Saginaw or Muncie. This feature increased the rigidity of the case significantly. Distinguishing the three speed from the four is as simple as counting the fasteners on the top plate. The four speed has ten; the three, nine. By 1967 both the three and four speed gearboxes were designed to function in constant mesh, due to synchronizer sleeves being used instead of sliding gears, and be fully synchronized, with the exception of reverse. Forward gears are helical-type while reverse gear and the exterior of the first and second synchronizers sleeves are spur-type gears. This transmission is also known as the Tremec T-170, HEH, or RUG depending on the year(s) of production.

Applications
Renowned for high-performance indestructibility, the Toploader, particularly the four speed, was equipped in such sought after "A-list" cars as the Mustang, Talladega, AC Cobra, AC Frua and Sunbeam Tiger as well as the Ford Fairlane, Falcon, Galaxie, Ranchero, Torino and the Mercury Comet, Caliente, Cyclone and Marauder. Overall the Toploader was used in 133 different models and was used extensively in racing as well.

Specifications
The Toploader comprises two components: the main case, which encloses the gears, input and counter shaft, and the tailhousing, which encloses the speedometer gear and output shaft. The main case measures 12" in length, while the tailhousing measures 14", 14 ½" or 17", depending on the application.

Shifter bosses are cast into the tailhousing along various points depending on the location of the shifter, as required for each model. Generally Falcons and Comets have shifters mounted forward along the housing, Mustangs rearward, and Fairlanes and full size Fords somewhere in between. Toploaders were also designed for two specific applications: small blocks like the Ford Windsor engine, and big blocks like the Ford FE engine and Ford 385 engine series. Big blocks required a larger "input shaft" to withstand the torque.

Toploader 4 speed Note: 1964 and early 1965 Toploaders came with 25 spline output shafts which subsequently proved to be defective and were quickly replaced.

Gear Ratios
Toploader 4 speed

Note: Gear ratio is determined by tooth count on second gear. Close ratio has 28 teeth, wide has 31.