GM 4L60-E (later version) Transmission

to the

Jeep & IH Models 18 & 20 Transfer Cases

Jeep Adapter kit to GM Bellhousings

Kit 4L62-3, adapting late GM 4L60-E transmissions to Jeep Dana 18 & 20 transfer cases

Our 4L60E (later version) to Dana Models 18 & 20 conversion makes for a tough 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.

The Novak 4L60-E to Jeep Dana transfer cases adapter is 6.5" long for a combined transmission and adapter length of 26.5" (equivalent to a 19.5" manual transmission).

The adapter is comprised of two main components. The transmission spacer is machined of aluminum alloy. The transfer case side 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 gear is rigidly supported by this configuration to handle gear side loads.

Kit contains:

  • Adapter housing
  • Transmision spacer
  • Transfer case adapter shaft (choose your spline count)
  • Bearings
  • Seals
  • Reluctor ring, clamp-on
  • Vehicle Speed Sensor, GM version
  • Transfer case to adapter gasket
  • Transmission to adapter sealing ring
  • Fastening hardware
  • Modular steel mounting base
  • 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.

Compatible Transfer Cases

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.

While it is mechanically possible to run the overdriven 700R4/4L60E assembly against a Dana 18 that features a Warn style overdrive, consider that you would have an overall overdrive ratio of .525 (.70 in the transmission and .75 at the transfer case overdrive). Transfer case output speed would be nearly double that of the engine speed. While this is a fascinating thing and excellent for mileage if the engine can sustain the low RPM cruise, the velocities that it could turn within your Dana 18 may be overwhelming. Keep in mind that the D18 and its overdrive were not designed for that type of RPM use. you would likely run into oiling issues at those sustained speeds.

Transfer Case Input Gear

Jeep Dana 18 or 20 Input GearOur 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.

Consult our informative Dana gears interchange chart if necessary.

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

Dana 18 or 20 Input Gasket


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.

Compatible Engines

Any engine that can be made to work with the 4L60E will work with this adapter. Natively compatible engines such as the 1997-2006 Vortec / LS / Gen III+ engines are far and away the most popular choices.

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, 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 depart 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 only have reverse, third gear and max line pressure; probably not the best solution for a Jeep.

Be careful when working with a Gen IV version of a 4L60E transmission. They feature a special Transmission Control Module that is very picky about the engine and it's controller. We recommend sticking with the matched Gen III style 4L60E transmission control systems.

Lastly, be aware of Gen III engine crank spacing, 4L60E flexplates, 4L60E bellhousing depths, and torque converter heights. This is not much of an issue where installers have pulled a factory matched engine / transmission combo as their donor, whereas those who are mixing and matching LS components should verify accordingly. We've written a helpful guide to GM crank spacing here.

Compatible 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. These are strong transmissions native to 1/2 ton truck, SUV and sports car applications. Full Size Jeeps such as Wagoneers, J-Trucks, etc. are conversion candidates for them. There are numerous upgrades available for the 4L60E 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.

Related Products


Urethane Rear Mount for Crossmember
4L60-E 4wd output shaft
Auto transmission cooler
Dana 18 & 20 Input Gears
Dana 18 & 20 Rebuild Kit
Dana 18 Billet PTO Cover
Dana 20 billet rear bearing cap
Billet aluminum Dana transfer case pan
TurnKey 4L60E Transmission Package

Installation Requirements

Driveshafts

Driveshaft length changes are often required. Most conversions to these transmissions will require that the rear driveshaft be modified to be shorter and front driveshaft longer.

Some installers, concerned about the expense of new or modified driveshafts, attempt to let the existing driveshafts dictate engine, transmission and transfer case location, often to the detriment of the project. Our recommendation is to prioritize the correct position of drivetrain components over saving a few dollars which is usually regretted in the long run with compromised positioning.

Driveshaft modifications and rebalancing can be affordable when performed by driveline, RV or tractor implement specialists. New driveshafts are an option, but not necessarily a requirement in regards to the actual successful conversion if your existing driveshafts are in good condition.

Jeeps that require extensive travel or specialty-built driveshafts have this option available through several fabricators across the nation. These are normally specified after placement of the new transmission and measured at vehicle ride height. As the rear driveline gets shorter, it is often advantageous to us a Double Cardan or “CV style” rear shaft with the correct geometry at the axle to minimize vibrations and possible binding.

Axles

Use of factory axles is completely acceptable with this conversion. Axle upgrades are not necessary, but they may be chosen for reasons external to this transmission upgrade.

Tools

Tools required will vary depending on which kit is selected. The automatic transmission takes more specialized tools, knowledge, gaskets, seals, snap ring pliers, etc. The adapter requires typical mechanic's hand tools.

Placement

Transmission placement is largely determined by factory engine location. It is not necessary in typical conversions to change the engine position unless an engine is being swapped in at the same time as will often be the case with these kits. Setting the powertrain to the proper factory or conversion pitch angle - usually tilted down ~5 (3-7 acceptable) degrees - is recommended. Consult our engine conversion guides for more specific recommendations on placement if the engine is being replaced.

Clocking Information & Driveshaft / Yoke to Pan Clearance

Use of the factory size driveshaft and yoke is recommended. Our adapter design has maximized clearance between the transmission pan and yoke, but it is necessary that you install your GM engine offset 1-1/4" to the driver's side.

Engines & Engine Mounting

If converting to a V8 in conjunction with this upgrade, aftermarket engine mounts are available to ease its installation. Because of the broad spectrum of engines and vehicle combinations used with this adapter, it would be difficult to list them all here. Whatever your application, Novak likely has the perfect solution. From a 225 Buick V6 in a CJ2A to an LS3 in your JK we’ve got you covered.

GM to Jeep Engine Mounts

Novak's engine mounts, featuring excellent vibration dampening, superior strength and impressive adjustability - adjustable even after the engine is installed. The design and strength and affordability of our mounts are second to none.

Engine placement in these applications is an effort in compromise to find the best position overall as a package. Generally the engine will be about 1” or even more towards the left, (driver’s side in the USA) away from the front differential in a CJ application. This gives the best balance of weight and more importantly clearance for the driveshaft going to the front axle. your tight spots will be steering to exhaust on the left (hold that as tight as you can) and clearance for the front driveshaft on the right. Fore and aft position will vary with the Jeep model and engine. Have a CJ5 and Gen I with a rear distributor? you’ll be better off a little forward for more rear driveshaft length and clearance for that HEI. If you are in a longer Jeep and using an LS engine with no distributor, you’ll have more fan clearance and better balance if you hold it to the rear. Usually for ground clearance tuck things up nicely for height to avoid damage to oil pans and other life giving parts in the Jeep. Common sense and taking a step back to look at things overall goes a long way.

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