Ford Transmission ID, toploader FMX C4 C6


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Ford 4 speed toploader transmissions ID decoding

Toploader speed calculator


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Mustangtek Differential and  Transmission Ratio Calculator


Ford 4 speed Toploader

Built Ford Tough.

The 4 speed toploader is one of the toughest manual transmissions ever built.

Identification of the Toploader is easy. Toploaders are top accessible (from a 10 bolt steel plate)

For decoding the specific application look for a metal tab riveted on the right side of the transmission body housing.

HEH-? or RUG-? are the codes necessary for decoding specific transmission application from the

4 speed Toploader Identification page


Close and Wide Ratio

2 types of gear ratio are commonly associated with the 60's 70's toploader

Ratio type
1 rst
2 nd
3 rd
4 th
Close ratio
Wide ratio

Ratio chart page gives a good idea of rpm, speeds and shifting points for both Close and Wide ratio transmissions.


Decoding the Toploader

For most 60's and 70's Toploaders the ID starts with either prefix HEH or RUG


Transmission identification code

HEH-D = 64 390 Galaxie, 1 1/16" input shaft, 28 spline output, close ratio

Transmission serial number

Transmission identification code

RUG-AV1 = 70-71 302-351 Mustang, 1 1/16" input shaft, 28 spline output, wide ratio

Transmission serial number

4 speed Toploader Identification page

The lower number on the tag is the transmission serial number. The transmission serial number is a production serial number and should not be confounded with the engine serial number, they are not the same. Some transmissions have a date code instead of the serial number.


Input Shaft

2 different INPUT shaft are commonly available for all V8 Ford's, 1 1/16" and 1 3/8". But both input shafts have the same number of splines of 10.

1 1/16 " input shaft

1 3/8 " input shaft

10 spline
10 spline



Also 2 popular OUTPUT shafts are available for the V8 toploader a 28 spline or a 31 spline shaft (sorry, no pictures)


Tailshaft housing

Many different Tailshaft housings and shifter positions available with Toploaders.

here are a few


Wide transmission insulator  mount

Narrow transmission insulator  mount
Narrow transmission insulator mount
Wide transmission insulator  mount
Wide transmission insulator mount
Wide transmission insulator  mount
Wide transmission insulator  mount


Bolt patterns (bellhousing)

2 different bolt patterns. Early Toploaders used a narrow bolt pattern type for attaching the transmission to the bellhousing and the later versions used a wider butterfly type bolt pattern.

Narrow bolt pattern

Butterfly bolt pattern

Early type
Later type


Toploader exploded view


Ford Borg & Warner T-10

Ford T-10 Borg & Warner application chart



Several versions of the T-10 where offered for 1960-66 Fords. Towards the later years the cast iron versions where mainly used on small cars. Early Cobra's and 65 Shelby's used and all aluminum T-10 while a variety of all aluminum and part aluminum and full iron ended up used on 66 Shelby's.

All Shelby's used a close ratio gear set.

Ford cars used wide ratio T-10's and several different wide ratios where used on non Shelby cars.


2 different casings available. Narrow bolt type and the later butterfly type

Narrow bolt pattern

Butterfly bolt pattern

Early type
Later type

C4 application chart

C4 transmission can easily be identified by the 11 bolt oil pan

Tailshaft housing


Wide transmission insulator  mount


C6 application chart


FMX FX MX application chart

3 speed (3.03)

3 speed application chart

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