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Novak Conversions

Transmission Knowledge Gateway

The transmission is central to any conversion, both physically and in terms of planning. Making the better choices in a transmission can determine the success, ease and affordability of the rest of the project. Here is our guide:

The transmissions we are most often asked about by our customers include:

Jeep Transfer Cases

Automatic Shift Transmissions

The 4L60E presents the culminated engineering greatness of five decades of GM automatic power transmission design

  • Compatibility with modern GM engines
  • An electronically operated transmission that is controlled by the integrated Powertrain Management Computer
  • Aluminum alloy case with non-integral bellhousing
  • Very durable, geared well and smooth operating in both street and off-road environments
  • Adaptable to essentially all of the Jeep transfer cases
  • 1997-present GM vehicles

The 700R4 is the great result of what happens when a good company like GM just sticks with it. People used to laugh at this transmission's early bugs. No one is laughing now. It's a top choice in some of the best Jeep upgrades out there

  • Compatibile with classic and modern GM engines
  • Either hydraulically (700R4 / 4L60) or electronically operated (4L60E) transmission
  • Aluminum alloy case with integral bellhousing
  • Very durable, geared well and smooth operating in both street and off-road environments
  • Adaptable to essentially all of the Jeep transfer cases
  • 1982-1996 GM vehicles

The TH350 is tough, compact and consistently a very popular choice for a Jeep upgrade transmission

  • Compatibile with classic and modern GM engines
  • Self-shifting hydraulic control
  • Aluminum alloy case with integral bellhousing
  • Strong and smooth operating in both street and off-road environments
  • Adaptable to essentially all of the Jeep transfer cases
  • 1969-1984 GM vehicles

The TH400 is the Big Daddy of the GM automatics. Brutally tough, relatively efficient and totally buildable

  • Compatibile with classic and modern GM engines, as well as AMC I6 & V8 engines
  • Self-shifting hydraulic control
  • Aluminum alloy case with integral bellhousing
  • Strong and smooth operating in both street and off-road environments
  • Adaptable to essentially all of the Jeep transfer cases
  • 1964-1995+ GM vehicles

The AW4 transmission was a step into the modern era for Jeep, with its overdrive and electronic control

  • Compatibile with AMC I6 engines
  • Electronic control, via its own computer or an integrated PCM
  • Aluminum alloy case with non-integral bellhousing
  • Moderate strength
  • 1987-2001 Jeep XJ

 

Manual Shift Transmissions

- Four Speeds -

The GM SM465 is said to be one of the greatest four-speeds ever built.

  • Compatibility with GM and AMC style engines
  • Iron case and top cover. Deep first gear with direct-drive in fourth
  • Brutally strong, but refined for road and trail manners
  • Adaptable to essentially all of the Jeep transfer cases
  • 1968 - 1991+ GM trucks

The Borg-Warner T18 & T19 transmissions are famous in the truck and off-road world, and this reputation is well earned.

  • Compatibility with GM, Ford and AMC style engines (Ford & Jeep versions)
  • Iron case and top cover. Deep first gear with direct-drive in fourth
  • Extremely strong, but with good road and trail operaion
  • Adaptable to essentially all of the Jeep transfer cases
  • 1966 - 1991+ Fords & Jeeps, primarily

The New Process 435 is a supremely good four-speed with an excellent history

  • Compatibility with GM, Ford, Dodge and AMC style engines
  • Iron case and aluminum top cover. Deep first gear with direct-drive in fourth
  • Tough as nails, but shifts nicely on the street and trail
  • Adaptable to essentially all of the Jeep transfer cases
  • 1966 - 1991+ Dodge & Ford trucks, primarily

The SM420 may be the king of the four-speeds. It has the deepest first gear of them all

  • Compatibility with GM and AMC style engines
  • Iron case and top cover. Deep first gear with direct-drive in fourth
  • Extremely strong, but quite roadworthy
  • Adaptable to essentially all of the Jeep transfer cases
  • 1947 - 1967 GM trucks

The T98 transmission is the predecessor to the T18 and similar in appearance and design

  • The Jeep version is adaptable with GM engines
  • Iron case and top cover. Deep first gear with a direct-drive in fourth gear
  • Plenty strong for any Jeep
  • Retained with the native Jeep transfer case
  • 1955 - 1971 (in Jeeps)

The T176 (and T177 / T178) is native to 1980 - 1986 Jeeps as the medium duty upgrade

  • Compatibility with AMC I4 & I6 engines, and adaptability to GM and Ford engines
  • Aluminum case and top cover. Close-ratio first gear with direct-drive in fourth gear
  • Stronger than the base-option transmissions during this era
  • Compatible with the Dana 300
  • 1980-1986 Jeeps

The SR4 is a car transmission that was installed in CJ Jeeps for two years

  • Compatible with AMC I4 & I6 engines
  • Aluminum case and top cover. Close-ratio first-gear and direct-drive in fourth
  • Neither strong, nor suited to conversions or serious off-road use
  • 1980-1982 CJ Jeeps

The T4 was the standard four-speed in the 1982-1986 CJ

  • Compatible with AMC I4 & I6 engines
  • Aluminum case and top cover. Close-ratio first-gear and direct-drive in fourth
  • Neither strong, nor suited to conversions or serious off-road use
  • 1982-1986 CJ Jeeps

- Five Speeds -

The AX15 is a surprisingly strong transmission, and was a serious improvement over many of its lighter-duty predecessors

  • Compatibility with AMC I6 and other engines, and adaptability to GM and Ford engines
  • Aluminum case. Decently low first gear with overdrive in fifth-gear
  • Surprisingly tough
  • Compatible with the NP231 and adaptable to the Dana 300, Dana 20 and Dana 18
  • 1988-1999 Jeeps

The NV3550 was New Venture's answer to the AX15, and in the same strength, operational and size category

  • Compatibility with AMC I6 engines, and adaptability to GM and Ford engines
  • Aluminum case. Decently low first gear with overdrive in fifth-gear
  • Surprisingly tough
  • Compatible with the NP231 and adaptable to the Dana 300, Dana 20 and Dana 18
  • 2000-2004 Jeeps

The NV4500 is a heavier-duty five-speed as found in full size GM and Dodge trucks

  • Compatibility with GM & Dodge engines with adaptability to AMC engines
  • Iron case with aluminum top cover . Fairly low first gear with overdrive in fifth-gear
  • Quite strong
  • Adaptable to the Jeep Dana 300 and NP231
  • 1993-present GM and Dodge trucks

 

The T5 was the standard five-speed in the 1982-1986 CJ

  • Compatible with AMC I6 engines
  • Aluminum case and top cover. Close-ratio first-gear and overdrive in fifth gear
  • Neither strong, nor suited to conversions or serious off-road use
  • 1982-1986 CJ Jeeps

The AX5 was the light-duty, five-speed transmission in the 1984-2003 XJ, YJ & TJ Jeeps

  • Compatible with AMC I4 engines
  • Aluminum case and top cover. Close-ratio first-gear and overdrive in fifth gear
  • Neither strong, nor suited to conversions or serious off-road use
  • 1984-2003 XJ, YJ & TJ Jeeps

The Peugeot BA10/5 had a gratefully short run in Jeeps

  • Compatible with AMC I6 engines
  • Aluminum case and top cover. Close-ratio first-gear and overdrive in fifth gear
  • Neither strong, nor suited to conversions or serious off-road use
  • 1987-1988 XJ, YJ & MJ Jeeps

- Three Speeds -

The T90 is the most famous of the Jeep three-speed transmissions

  • Compatible with Willys I4 & I6 engines and adaptable to GM engines
  • Iron case and top cover. Close-ratio first gear with direct-drive in third-gear
  • Fairly strong and extremely compact
  • Compatible with the Dana 18 and easily adaptable to the Dana 20
  • 1946-1971 Jeeps

The T150 was strong, and the last of the Jeep three-speeds

  • Compatible with AMC engines and adaptable to GM and Ford engines
  • Iron case and top cover. Close-ratio first gear with direct-drive in third-gear
  • Fairly strong and extremely compact
  • Compatible with the Dana 20
  • 1976-1979 Jeeps

The T15 was the strongest of all the three-speeds

  • Compatible with AMC engines and adaptable to GM engines
  • Iron case and top cover. Close-ratio first gear with direct-drive in third-gear
  • Very strong and quite compact
  • Compatible with the Dana 20
  • 1972-1975 Jeeps

The T14 is the T15's little brother. Not too tough but a pretty good gearbox

  • Native to Buick then AMC engines and adaptable to GM engines
  • Iron case and top cover. Close-ratio first gear with direct-drive in third-gear
  • Moderate strength and fairly compact
  • Compatible with the Dana 18 & 20
  • 1968-1975 Jeeps

The T86 is kind of a T90 knock-off. It was the transmission first offered with the Buick V6 engine

  • Compatible with the Buick V6 engine
  • Iron case and top cover. Close-ratio first gear with direct-drive in third-gear
  • Moderately strong and compact
  • Compatible with the Dana 18 readily Dana 20
  • 1946-1971 Jeeps

- Six Speed -

The NSG370 has the Benz air about it. Lots of gears and a unique, but durable design

  • The NSG370 replaced the NV3550 and was offered behind both the 4.0L Engine as well as a version behind the Mopar 2.4L I4. It is generously rated for torque handling
  • Aluminum case with integrated bellhousing
  • Compatible with the Jeep NP / NVG transfer cases.
  • 2005-present Jeeps