Novak Conversions Adapter 4L62-3-6 Kit

Adapting the GM 4L60-E (later version) Transmission to the Jeep & IH Models 18 & 20 Transfer Cases

Our 4L60E (later version) to Dana Models 18 & 20 conversion makes for a very strong and capable assembly both on-road and off-road. Because of the assembled length, this kit is only intended for longer wheelbase Jeeps, and other specialty conversions, such as Land Rovers, Land Cruisers, and other vehicles in which Jeep transfer cases would be useful.

Product & Features

About the Adapter

The Novak 4L60-E to Jeep NP / NVG transfer cases adapter is 5.5" long for a combined transmission and adapter length of 26.5" (equivalent to a 19.5" manual transmission).

Advanced computer modeling methods were integral to the design of our #4L62 adapter assembly.

The adapter is comprised of two main components. The transmission half is machined of a 6061T6 billet aluminum alloy, featuring thick flanges and a heavy cross-section. The transfer case half is comprised of cast and machined high-grade aluminum alloy, featuring thick flanges, a heavy cross-section, and strength-adding gussets. The adapter shaft is machined from triple-alloy gear steel and provides superior strength as it is carried by two bearings unlike the other single bearing versions on the market. The Dana 18/20 input is completely supported by this shaft and, due to the helical cut, is subject to side loading. The two bearing design is much better equipped to handle these loads.

Contents

The 4L62 Kit includes adapter housings, adapter shaft, bearings, seals, correct locator for your transfer case model bore, sensor with reluctor, hardware, and instructions. These parts will come assembled to the extent possible. 

Applications & Compatibility

4L60-E Versions

This kit is for use with the 4wd version (short output shaft) version of the 4L60E. However, a 2wd version transmission can be used if a 4wd style shaft is installed. Once the 4wd shaft is installed, there are no inherent advantages to the 2wd vs. 4wd transmission. These kits are for the hexagonal, six-bolt tailhousing 4L60-E, typically made starting in 1996. Some 1999 and earlier versions have a four-bolt pattern tailhousing and non-removable bellhousing. See our Kit #107 if this describes your transmission.

The 4L60E is an electronically controlled transmission and requires a computer to control it. If you are transplanting a complete engine/transmission package then the controller is likely there. If not, you will need to purchase a control module for proper operation. We have two versions available below if you need one of those.

Jeeps

This kit is only intended for longer wheelbase Jeeps, and other specialty conversions, such as Land Rovers, Land Cruisers and other vehicles in which Jeep transfer cases would be useful. These are strong transmissions, and Full Size Jeeps such as Wagoneers, J-Trucks, etc. are conversion candidates for them. There are numerous upgrades available for the Transmission should stock strength come into question. 

The TH350 is the only real automatic option practical for CJ5 and other short wheelbase Jeeps. Our 103 kits are best for these versions. 

Engines

Any engine that can be made to work with the 4L60E will work with this adapter. All of the above mentioned native engines along with others that can be adapted via a front adapter such as our 437 series kits open up numerous possibilities.

There were also a lot of other combinations available to the 4L60E that may not be perfect candidates for a Jeep swap. The Atlas series inline engines, 3.8L in the 90’s era Camaro, a rear configuration for the Corvette, and there is even a Bellhousing available in Australia for the Holden that will allow a High Feature DOHC V6 to mate to the 4L60E. Sometimes just because it’s possible doesn’t make it a good idea, but we’ll leave that part up to you.

Keep in mind that if you stray from a native configuration on the engine, you will need an aftermarket controller for the transmission as these are electronically controlled both in the shifting and pressure. Without a controller you’ll have reverse, third and max line pressure, which is probably not the best solution for a Jeep.

Transfer Case Versions

All Jeep models of the Dana Spicer 18 and Dana Spicer 20 transfer cases are compatible with this adapter assembly. IH versions of these transfer cases are also compatible. The correct input bore and spline count must be observed. This adapter is not suitable for the Ford Bronco transfer case as it is of an entirely different design in attachment and drop.

Transfer Case Input Gear

Our adapter shaft is splined for six spline input gears.

• Six-spline gears (shown, right) are most common and usually found behind Jeep T84, T90, T86, T89, T98, T18, T15 & T150.
• The ten-spline version was only available on the 1966 - 1974 transfer cases against the Jeep T14 transmission
• Factory Jeep TH400 to Dana 20 combinations had a fifteen-spline input gear, which must be replaced by a compatible six spline version.
• International Harvester Dana 20's that had the TF-727 automatic had a 23-spline input gear, which must be replaced by a compatible six spline version.

All Warn and Saturn type overdrives are compatible with this conversion as long as the spline count is correct. We do not have replacement gears for the overdrive version.

Transfer Case Bore Size

The diameter of the transfer case center input locating bore will be either 3-5/32" or 4".

• Most Dana 18's have a 3-5/32" bore, including those found against the T84, T90, T89 or T98.
• Some Dana 18's have a 4" bore, including those found against the T86 & T14 transmissions (Buick V6 engines), 1966-1971.
• All Dana 20's have a 4" bore, regardless of the transmission they were joined to.