The Ford Toploader Transmission was introduced in 1964 to replace the Borg Warner T-10. This is the super-tough transmission built by Ford Engineers to stand up to just about anything demanded from it. Internal parts of the toploader are assembled through the top of the case instead of through a side cover, thus the name “Toploader”. This design is actually stronger than a 4-speed box with a side cover. The shifter rails are mounted in bosses that are cast into the box itself, leaving the only function for the topcover to keep the lube inside.

The toploader 4-speed transmission is the fully synchronizer type with all gears except the reverse sliding gear being in constant mesh. All forward-speed changes are accomplished with synchronizer sleeves instead of sliding gears. The synchronizers will enable quicker shifts, greatly reduce gear clash, and permit down-shifting into any forward-speed gear while the car is moving. All forward-speed gears in the transmission are helical type, however the reverse sliding gear and the exterior of the first and second-speed synchronizer sleeve are spur-type gears.

Image borrowed from RacingJUNK Racing a& Performance Classified. It’s called a toploader due to the access from the TOP of the transmission which is easy to see in this picture.

FORD TOPLOADER BELLHOUSING IDENTIFICATION
289-302 1968 C8AA-6394-A Aluminum
302 1968 – 1969 C8AA-6394-B Iron
302 1969 – 1973 C5AA-6394-B Aluminum

A 1 1/16” input shaft was used with motors from the 200 c.i. to the 390 c.i. while the 427, 428, and 429, used a large 1 3/8” input shaft. The 427, 428, and 429 were available only with close ratio gears. While the 1 1/16” input transmissions were available in both close and wide gear ratios.

1965-73 cases were wide 8 hole cases with the large outside diameter bearing retainer.

In the first 91 days of toploader production, a few transmissions used a 25 spline output shaft which proved to be defective. These were quickly dropped from production. Normally, all motors 200 c.i. – 390 c.i. use the 28 spline output shaft. All 427, 428, and 429 motors use the 31 spline output shaft.#


GEAR RATIOS
First Gear ratio
w/Stock 32 tooth
First Gear ratio
w/DWT 33 tooth
First GearSecondThirdFourthReverseFirst Gear
Close Ratio:2.321.691.291.12.322.40
Wide Ratio:2.781.931.361.12.782.90

My RUG Transmission is a Close ratio with the above gears.


#Source of information: Toploadertransmissions.com Dan Williams. This is where I got the parts to rebuild my transmission.

Picture of the interior of my car. The wood grain console is unique to 1968 Shelby Mustangs. I swapped out the stock Ford shifter for a Hurst unit. And I had to put a T handle on the end of it. Using this shifter moved Reverse gear position from the bottom left to the upper left on the pattern. Which is no problem if you know that. But the pattern is NOT displayed on this T Handle.

Summary and comment on this transmission with the car today.

The toploader transmission is still one of the most awesome and strongest transmissions ever built for the street. You would be hard pressed to find a transmission to match this one in a 5 speed. But the concern right now is with that 3.89 rear end gear the engine is turning 3300 rpm at 60 mph. It needs an override gear. On my wish list to either put a 5 speed in it or a 2 speed axle. If I drove it more it would be a real priority.

When it was time to rebuild this transmission I had to look for parts. Toploaders are no longer offered by Ford. Tons were put into Ford cars, but new parts were pretty scarce. I obtained a full set of new parts from Dan Williams Toploader Transmissions. His company makes parts of heavy equipment transmissions. He loves Mustang Bosses and ended up making parts to fit those transmissions.