Toploader Transmission Identification Guide

Ford's Toploader four-speed went into Mustangs, Cougars, Fairlanes, Galaxies and most other Ford and Mercury cars from 1964 to 1973. Each one left the factory with a small tag, and the code on it, such as HEH-BX or RUG-E2, tells you which gearset is inside (close or wide ratio), how many splines the output shaft has and which cars and engines it was built for. Find your code in the table below. It covers all 112 four-speed codes from 1964 to 1973.

The name comes from the way it's built: the gears go in through a cover on top of the case instead of a cover on the side. Once you know your gearset, the gear ratio calculator shows your speed in each gear at any RPM.

Where to find the Toploader tag

The tag is a small metal tag on the passenger side of the main case, near the front. Like any tag it can be painted over, rusted thin or lost during a rebuild. If yours is gone, the gearset can still be found by counting teeth or turning the input shaft, and the output shaft's splines can be counted.

Ford also stamped part of the VIN on the cases of some high-performance cars (Boss, Cobra Jet and Mach 1), on the upper ear on the driver's side. Some early K-code Mustangs have the full VIN on the bottom of the case.

How to read a Toploader tag

The top line is the transmission code. Codes starting with HEH are mostly 1964–1966, with a few into 1967, and codes starting with RUG are 1967–1973. The letters after the dash identify the model, and some codes add a number: RUG-E, RUG-E1, RUG-E2 and RUG-E3 are all wide-ratio Mustang and Cougar codes from 1967 to 1969. The number on the lower line is a serial number, given in the order the transmissions were tagged. It has nothing to do with the car's VIN. Some tags carry a date code there instead.

RUG-E2, for example, is a wide-ratio Toploader with a 28-spline output shaft, listed for the 1967–1968 Mustang and Cougar with a 289 or 302.

Close or wide ratio

Every production Toploader four-speed in the table has one of two gearsets:

• Close ratio: 2.32 first, 1.69 second, 1.29 third and 1.00 fourth. Open it in the gear ratio calculator.
• Wide ratio: 2.78 first, 1.93 second, 1.36 third and 1.00 fourth. Open it in the gear ratio calculator.

Ford also built a dozen "white stripe" racing Toploaders for factory race cars, codes HEH-HA to HEH-HM, with gear ratios tailored to the car or track. They aren't in the table.

The close ratio's gears are nearer together, so the RPM drops less on each shift, which suits an engine that makes its power high in the rev range. Every 427, 428 and 429 Toploader in the table is close ratio. The wide ratio's lower first gear gets a milder engine moving more easily, and it's the more common of the two behind the smaller engines.

Two ways to tell them apart without a tag:

• Count second gear's teeth. With the top cover off, second gear on the mainshaft has 28 teeth in a close-ratio box and 31 teeth in a wide-ratio box. This also settles the three codes the charts disagree on (see the Notes column).
• Turn the input shaft. With the transmission out of the car and in first gear, turn the output shaft one full turn and count the turns of the input shaft: about 2 1/3 turns for close ratio, about 2 3/4 for wide.

Show only close-ratio tags or only wide-ratio tags.

Input shaft and output shaft splines

The input shaft has 10 splines. The 200 through 390 engines use a 1 1/16" shaft. The 427, 428 and 429 use a separate big-block input shaft; sources give it as 1 3/8" for the 428 Cobra Jet and 429. The clutch disc has to match the input shaft. The table states an input shaft size only for the tags a source measured; the rest follow the engine.

The output shaft has 25, 28 or 31 splines, and the driveshaft's slip yoke has to match it:

• 25-spline: 1964 to early 1965. Ford dropped it as too weak; the last Mustang codes with it (HEH-P) were built until December 30, 1964.
• 28-spline: usually the 200 through 390 engines from then on. The exceptions are the Comet, Fairlane and Torino 351 codes RUG-AK, RUG-AS, RUG-AS1, RUG-BA1, RUG-BG, RUG-BG1 and RUG-BG2, which are 31-spline.
• 31-spline: usually the 427, 428 and 429. The 1964–1965 427 codes HEH-H, HEH-R, HEH-AT, HEH-CB and HEH-BY are 28-spline.

The driveshaft guide lists slip yokes by spline count. Show only 25-spline, 28-spline or 31-spline tags.

Main case and length

Cases built in 1964 and early 1965, to about February 1965, have a narrow four-bolt pattern on the front face, where the case bolts to the bellhousing; the 1964 casting number is C4AR-7006-A (one chart prints C4AR-7003-A). Later cases, through 1973, have a wide eight-bolt pattern, and its inner four holes line up with the narrow pattern. Later case castings are C5AR-7006-D (1965–1967), C8AR-7006-D (1968–1971), D2AR-7006-CA (late 1971) and D2AR-7006-CB (1972–1973).

Toploaders came in three overall lengths, depending on the car:

• 24": every Mustang, Cougar, Falcon and Maverick, the 1966–1967 Fairlane and Comet, and the AC Cobra 427/428. One chart lists a 24 1/2" case for the 1970–1971 Mustang codes RUG-AV and RUG-AV1.
• 25 1/2": the 1964–1965 Fairlane, and the Sunbeam Tiger, Griffith and TVR.
• 27": full-size Fords and Mercurys, and the 428 and 429 Cyclone and Torino.

Mustang and Cougar tailhousings

The tailhousing sets the transmission mount width and where the shifter bolts on, which matters more on a swap than the case does. Mustang and Cougar tailhousings are 14" long:

• C4DR-7A040-A: narrow mount. Rear shifter holes drilled and tapped, lower front pads machined off. 25- or 28-spline. The same casting drilled for a front shifter went on the 1964–1965 Falcon.
• C4ZR-7A040-A: narrow mount. 1964–1973 Mustang and Cougar 289, 302 and 351. 25- or 28-spline.
• C6OR-7A040-C and C7OR-7A040-A: wide mount. 1966–1969 Mustang and Cougar 390 (28-spline) and 1968–1969 Mustang 428 and 429 (31-spline).
• D0ZR-7A040-A: wide mount. 1970–1971 Mustang and Cougar 428, 429 and Boss 429. 31-spline.

Falcons and the later Fairlanes and Comets also used 14" tailhousings, and the 1964–1965 Fairlane a 15 1/2" one. Full-size cars used 17", as did the 1969-on Cyclone and Torino with a 428 or 429.

Is it a real Toploader?

Ford's 1977–1978 three-speed with overdrive looks like a Toploader, and its tags start with RUG too: RUG-BP, RUG-CA, RUG-CL and RUG-CD. It isn't in the table below. Signs you have one:

• Case casting numbers starting with D7DR, and on some, ORION cast into the driver's side.
• Four bolt holes on the front of the case instead of eight.
• A bulge on the passenger side of the case for the overdrive gear.
• The shifter holes on the tailhousing won't suit an early car, and the speedometer pickup is on the opposite side from a Toploader's.
• Inside, a small gear where a Toploader's third gear would be.

Bellhousings and speedometer gears

A Toploader needs a car bellhousing 6 1/4" deep; a 6 3/4" truck bellhousing is too deep. The bellhousing also has to match the case's front pattern, narrow for cases built through early 1965 and wide after that, and the engine's flywheel and starter. The bellhousing, flywheel and clutch guide covers what goes together on the six and the small-block V8.

The Toploader's speedometer cable enters on the passenger side, so it takes a left-hand (Type 3A) driven gear, sold in 17 to 21 teeth. The right-hand gears made for the T5 and C4 won't work in it. The drive gear inside the transmission is usually a black 7-tooth gear for 2.80 to 3.50 axle ratios or a pink 6-tooth for 3.50 to 4.11. The tooth math is the same as a T5's, so the T5 speedometer gear calculator still gives the driven gear's tooth count: enter the drive gear's teeth, your tires and axle ratio, then buy that tooth count as a Type 3A gear made for the Toploader. Ignore the calculator's gear colors and part numbers, which are for the T5.

What the columns mean

• Tag: the code on the tag. Select it to get a link to that row.
• Years, Vehicles and Engines: the model years, cars and engines the code was listed for. The table merges two published charts; where their years differ, it shows the span of both. 2V and 4V are two- and four-barrel carburetors.
• Ratio: Close or Wide, the two gearsets described above. Select it to open that gearset in the gear ratio calculator. Close or wide means the two charts disagree; count second gear's teeth to be sure.
• Output Spline: the number of splines on the output shaft, which the slip yoke has to match.
• Notes: build dates (Built before 8/20/64), where the charts disagree, the input shaft size where a source states it, and the case and tailhousing castings seen on real transmissions with that tag.

A blank cell means nothing is listed. Ford changed parts during a model year and transmissions have been swapped between cars for decades, so treat the Vehicles column as a guide, not proof of what a car came with.

Mustang Toploader tag codes

Every code in the table below that lists a Mustang or Shelby, 1964½ to 1972. Most were shared with the Cougar, and some with the Falcon, Fairlane and Comet; select a code to see every car it was listed for.

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Tag	Years	Engines	Ratio	Output Spline	Notes
HEH-A	1964	260	Wide	25-spline	One chart lists this tag for the 1964½ Mustang 260. Seen with case C4AR-7006-A
HEH-BR	1965	260, 289 2V/4V	Wide	28-spline	Built 12/30/64 to 2/1/65
HEH-BT	1965	289 2V/4V	Close or wide	28-spline	Built from 2/1/65. The charts disagree on the ratio; count 2nd gear teeth (28 close, 31 wide). Seen with case C5AR-7006-D
HEH-BW	1966	289 2V/4V	Wide	28-spline	Seen with case C5AR-7006-D
HEH-BX	1965–1966	289, 289 Hi-Po	Close	28-spline	Built from 10/1/64
HEH-C	1964	289 Hi-Po	Wide	25-spline	One chart lists this tag for the 1964½ Mustang 289
HEH-G	1964	260, 289 4V	Wide	25-spline	Built before 8/20/64. 1 1/16" input shaft
HEH-P	1964	289 2V/4V	Wide	25-spline	Built 8/20/64 to 12/30/64. Seen with case C5AR-7006-D
HEH-S	1964½	289 Hi-Po	Close		Built before 8/20/64
HEH-T	1965	289, 289 Hi-Po	Close	28-spline	Built 8/20/64 to 10/1/64. Seen with case C5AR-7006-D, tailhousing C4DR-7A040-A
RUG-AD	1968	390 GT 4V	Close	28-spline	Seen with case C8AR-7006-D, tailhousing C7OR-7A040-A
RUG-AD1	1969	390 4V	Close	28-spline
RUG-AE	1968	428 CJ	Close	31-spline	1 3/8" input shaft. Seen with case C8AR-7006-D
RUG-AE1	1968–1969	428 4V	Close	31-spline
RUG-AE2	1969	428 CJ, 429 4V, Boss 429	Close	31-spline	1 3/8" input shaft. Seen with case C8AR-7006-D, tailhousing C7OR-7A040-A
RUG-AG	1969	302 2V, 351 2V/4V	Close	28-spline	Seen with case C8AR-7006-D, tailhousing C4ZR-7A040-A
RUG-AV	1970	302, 351, Boss 302	Wide	28-spline	24 1/2" long case
RUG-AV1	1970–1971	302 4V, 351 4V	Wide	28-spline	24 1/2" long case. Seen with case C8AR-7006-D, tailhousing C4ZR-7A040-A
RUG-AW	1970	302, 351, Boss 302	Close	28-spline	Seen with tailhousing C4ZR-7A040-A
RUG-AW1	1970–1971	302 4V, 351 4V, Boss 302	Close	28-spline
RUG-AZ	1970	428 CJ, Boss 429	Close	31-spline	Seen with tailhousing D0ZR-7A040-A
RUG-AZ1	1971	429 CJ	Close	31-spline
RUG-BJ	1971	351, 351 CJ, Boss 351	Wide	28-spline	Built before 12/1/71. Seen with case D2AR-7006-CB
RUG-BJ1	1972	351, 351 CJ, 351 HO	Wide	28-spline	Built from 12/1/71. One chart says Boss 351; its 1972 successor was the 351 HO
RUG-E	1967–1968	289 2V/4V	Wide	28-spline	Seen with case C5AR-7006-D, tailhousing C4ZR-7A040-A
RUG-E1	1967–1968	289 2V/4V	Wide	28-spline	Seen with tailhousing C4ZR-7A040-A
RUG-E2	1967–1968	289 2V, 302 4V	Wide	28-spline	Seen with case C8AR-7006-D, tailhousing C4ZR-7A040-A
RUG-E3	1969	302 2V, 351 2V/4V	Wide	28-spline
RUG-M	1967	390 4V	Wide	28-spline
RUG-M1	1967	390 4V	Wide	28-spline
RUG-M2	1968	390 GT 4V	Wide	28-spline
RUG-M3	1969	390 4V	Wide	28-spline
RUG-N	1967	289, 289 Hi-Po	Close	28-spline
RUG-N1	1967	289, 289 Hi-Po	Close	28-spline
RUG-N2	1968	289, 289 Hi-Po	Close	28-spline
RUG-N3	1968	289	Close	28-spline
RUG-S	1968	428	Close	31-spline	Seen with case C5AR-7006-D, tailhousing C6OR-7A040-D

Every Toploader tag code, 1964–1973