Novak Conversions

Transfer Case Knowledge Gateway

To an important degree, Jeeps are what Jeeps are because of their transfer cases. The chances are that your Jeep already has a great transfer case in it. So, read up and discover the details of this critical part of the mix that is your Jeep's powertrain.

The most significant transfer cases include:

Dana Spicer Model 18

Dana 18 Transfer case master rebuilt without emergency brake.

The original. The Model 18 is a significant part of history, yet it is still a very relevant transfer case for a great many enthusiasts.

1941-1971 military & civilian Jeeps and IH vehicles
Iron case, gear-driven, passenger-side offset drive for front and rear output shafts
Tough as nails, compact and easy to service
Adaptable to a broad variety of the great transmissions

Dana Spicer Model 20

The offspring of the Dana 18, the Dana 20 was the strong "silent-type" and it put a bit of refinement into 4wd.

1962-1979 Jeep CJ's, FSJ's , IH & Ford
Iron case, gear-driven, passenger-side offset drive for the front axle and centered output for the rear axle
Even stronger than its predecessor, yet still compact and easy to service
Adaptable to a broad variety of the great transmissions

Dana Spicer Model 300

The culmination of Dana's transfer case engineering, the Model 300 was the final coup in gear drive.

1980-1986 Jeep CJ's, and the 1980 IH
Iron case, gear-driven, pasenger-side offset drive for the front axle and centered output for the rear axle
Slightly stronger than its predecessor with improved gearing and operation. Servicability and durability are premier
Adaptable to more transmission options than any other

New Process / New Venture 231

Master rebuilt New Process 231 Transfer case.

The surprisingly great Model 231 is ubiquitous, enjoying a long production run and a great success in chain-drive.

1987-2006 Jeep YJ, TJ, XJ, MJ, ZJ as well as GM and Dodge applications
Aluminum alloy case, chain-driven, planetary-reduction, driver-side offset drive for the front axle and centered output for the rear axle
Tough, with a great low-range and a myriad of aftermarket improvements
Adaptable to the full array of excellent transmissions

New Process / NVG 241OR RockTrac

New Process 241 (1987 - present) and 241OR (2003 - present)

Jeep clues into the deep gearing craze and releases the Model 241OR RockTrac.

2003-current Jeep TJ / LJ / JK Rubicons
Aluminum-Magnesium alloy case, chain-driven, deep planetary-reduction, driver-side offset drive for the front axle and centered output for the rear axle
Very tough, with a supreme 4:1 low-range
Fully adaptable to a great variety of transmissions

New Process / NVG 242

Master rebuilt NP242 Transfer case for Jeep XJ .

The Model 242 is where things finally start to go well for a differential-ed transfer case

1987-2002 TJ, XJ, MJ, ZJ, KJ as well as GM and Dodge applications
Aluminum alloy case, chain-driven, planetary-reduction, driver-side offset drive for the front axle and centered output for the rear axle, integrated differential
Fairly strong
Adaptable to a great variety of transmissions

Borg-Warner 1305 / 1339 QuadraTrac

The QuadraTrac was revolutionary gearbox, though it had a bit of a bumpy ride.

1973-1979 Jeep FSJ & CJ
Aluminum alloy case, chain-driven, planetary-reduction, passenger-side offset drive for both front and rear axles
Quite strong, yet a bit complicated and requiring attention to chain stretch
Rarely retained in powertrain conversions

New Process 208, 219, 228 & 229

Chain drive hits the mainstream, if not yet its stride, in these early New Process transfer cases.

1980-1991 Jeep FSJ & early XJ
Aluminum alloy case, chain-driven, planetary-reduction, driver-side front offset drive for the front axle and centered rear output
Generally strong. Some models have viscous couplings, differentials and vacuum acutation, which take them out of the running for some serious Jeepers
Sometimes retained in powertrain conversions and adaptable to many excellent gearboxes

New Process 207

The Model 207 was the springboard for the Model 231. It was generally successful.

1984-1987 Jeep XJ and 1987 YJ
Aluminum alloy case, chain-driven, planetary-reduction, driver-side front offset drive for the front axle and centered rear output
Tough enough for many situations
Adaptable to a good selection of excellent transmissions

New Process 200

Military-grade strength is found in the Model 200, and the Model 200 is found only in the military M715 / M725 trucks.

1966-1971 Kaiser military trucks, and early Dodge militaries from 1947, onward
Iron case, gear-driven, passenger-side front output and centered rear output. Divorced mount
Outstanding strength
Usually retained in conversions with its factory T98, or used with 2wd style transmissions

Rebuild Guides

Guides for rebuilding early Jeep transfer cases.

Dana 18 & 20 Gears Interchange chart

A chart to determine gear compatibility