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AX15 installation kit for the 1966-77 Ford Bronco

Your Price: $1,020.80
Retail Price:$1,071.84
Your Savings:$51.04(5%)
Part Number:AA-27-3520AX15

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Advance Adapters

The AX15 transmission is an ideal transmission swap for the early Broncos. These 5 speeds are rated at 300 ft./lbs. at 7200GVW. A stock Bronco weighs 4200 GVW. When installed into a Bronco, the AX15 can then handle an even a higher torque rating due to the lower vehicle weight - so strength is not an issue. The weight of these 5 speeds is 97 lbs., which is like the stock 3 speed & 4 speed transmissions. The overall size and length make it an ideal fit. This transmission will adapt to either the stock Dana 20 or to our Atlas transfer case.

Kit Includes: Transfer case adapter, Dana 20 shifter bracket (T-shifter only), Ford bellhousing to AX15 adapter plate, clutch disc, full crossmember with rubber support and transmission shifter handle.

  • AX15 you supply.
  • No driveline modifications necessary.
  • The AX15 assembly is 1/4" shorter than the factory 3 speed or 4 speed.
  • The AX15 is slightly taller than the stock 3 or 4 speed. A 1" body lift is recommended for the best transmission alignment.

The Transmission:

This transmission is manufactured by Aisin Warner. The overall transmission case length is 24.000". The output shaft on this transmission is 23 spline and protrudes approximately .400". This transmission is normally found coupled to the AMC 4.0L 6 cylinder engine and seems to be one of the better transmissions Jeep used, being very capable of handling the horsepower and torque of a V8 engine.

The Vehicle:

The early Ford Broncos have always been a popular vehicle for conversions. These vehicles were normally equipped with a 6 cylinder or V8 engine up to a 3-speed transmission. On this transmission, Ford used two different lengths of adapter housings when coupling these 3 speeds to the stock transfer case. The adapter housing is either 6-1/2” or 9-3/8”. Vehicles equipped with a V8 had a 9-3/8” tailhousing which set the bellhousing further into the engine compartment. Vehicles with the 6-cylinder had a 6-1/2” tailhousing. This shorter adapter compensated for the longer engine. In 1973, Ford began offering the C4 automatic. A special tailhousing and output shaft was manufactured to couple this transmission to the stock transfer case. Ford no longer makes the C4 adapter.

The 1966-77 vehicles were equipped to a Bronco Dana 20 transfer case. This transfer case, unlike the Jeep Dana 20, has the front driveshaft on the driver’s side of the vehicle. The input gear of this transfer case is 6 spline. Ford always used a spud shaft that coupled this 6-spline transfer case to the transmission 28 spline.

The transmission-to-transfer case adapters used both a dowel pin and alignment retainer. The spud shaft is supported in this retainer with a bearing. The adapter kits we manufacture utilize this type of design. In some applications, we also retain the stock spud shaft*. This transfer case has a 2.46:1 low gear ratio. In early 1973, Ford switch to a 2.34:1 low gear ratio.

These transfer cases used two different shifter designs known as either the “J” pattern or “T” handle. The “T” handle was used from 1966 to 1972, and the “J” pattern from 1973 to 1977. The “T” handle shifter is a simple shifting mechanism and, to retain it with an adapter, only requires a pivot point for mounting. The “J” shifter requires the shift handle to be mounted in a location relatively close to its stock position. Retaining this shifter in its relatively stock location is hard to accomplish when adapting the various transmissions to the Dana 20. Vehicle owners having a “J” shifter is recommended to either change the transfer case shifter rods and go to a “T” style shifter or to contact one of the Bronco specialty shops that offer a twin stick replacement for the “J” shifter. A twin stick shifter replacing the “J” style should work with most of our adapters.

The adapter housings we manufacture normally utilize the stock Bronco crossmember with the stock rubber supports. On new transmission assemblies, longer than stock, this crossmember may need to be relocated. There are a few adapters that require this crossmember to be modified. These modifications are noted in detail on the specific adapter instruction sheet.

The Bronco Dana 20 transfer cases are a good, reliable transfer case; however, as with anything they do have some weaknesses. One problem area is the output shaft. With the increase of horse power and the reduction of gears, more stress and strain gets put on the transfer case output shaft. We are proud to be the manufacturer of a 32-spline output shaft for the Bronco Dana 20 transfer case. This output shaft was designed and engineered by Wild Horses of Stockton, California. This heavy-duty output shaft increases the output shaft straight up to 50% more than stock. This output shaft kit can only be purchased by contacting Wild Horses at (209)943-0991