Adapting the GM 4L60-E (later version) Transmission
to the
Jeep Dana Model 300 Transfer Case
and
Full-Size Jeep New Process Transfer Cases
Kit 4L63, adapting the GM 4L60E, 4L65E, 4L70E transmission to the Jeep Dana Model 300 transfer case
Our 4L60-E (including the 4L65 & 4L70) to the Jeep Dana 300 transfer cases conversion makes for one of the most refined assemblies both on-road and off-road. This kit has become one of our most popular transmission to transfer case combination.
The Novak 4L60E to Jeep transfer case adapter is compact at only 3.0" long for a combined transmission and adapter length of 25.5" (equivalent to a 17.5" manual transmission). The adapter itself is machined from 6061-T6 aluminum, featuring thick flanges, a heavy cross-section, and superior strength.
Kit Contents
- Adapter housing
- Transmission output shaft, 23 spline
- Reluctor ring, pressed on to shaft
- Vehicle Speed Sensor, GM version
- Transfer case to adapter gasket
- Transmission to adapter sealing ring
- Fastening hardware
- Modular steel mounting base
- Instructions
The new 23 spline 4L60E output shaft is machined from E4340 (similar to 300M) alloy steel which provides a substantial strength upgrade even over the stock 4L70E version. The new Novak shaft splines directly into the OEM style input gear of an NP transfer case. This requires disassembly of the transmission, and we recommend the services of a transmission professional.
Transfer Case Clocking & Rotation Options
Our adapter is drilled for multiple clocking locations from near-factory (20 degrees down) to near-flat (3 degrees down). However, pan clearances and front axle width may inhibit the flatter options.
Applications & Compatibility
Compatible Transmissions
The 4L61 adapter is compatible with all versions (2wd or 4wd) and years of the 4L60E, 4L65E & 4L70E transmission. We’ll refer to all these as 4L60E in this page but compatibility is all the same. For differences in these variations refer to this page. There are no inherent advantages to the 2wd vs. 4wd transmission as the factory output shaft will be replaced with the new Novak version.
These kits are for the hexagonal six-bolt rear pattern case made starting in 1996 and include a detachable bellhousing. Some 1999 and earlier versions have a four-bolt rear pattern and non-removable bellhousing. See our Kit #171-E if this describes your transmission.
The basic installation is a 2+ hour bench job and will include at least simple gasket and seal replacements. This is a good time for a more thorough master rebuild and update of the transmission. Many customers purchase one of our complete Novak remanufactured and upgraded transmission packages. The advantage of having a professionally built transmission that is tested, shipped and ready to bolt in is worth consideration.
Compatible Transfer Cases
Jeep Dana 300 Transfer Case
1980-1986 Jeep Dana 300's are compatible, so long as they have the 23 spline input shaft. If you have a shaft with a different spline count, it was likely a conversion transfer case in a previous project. If your 23 spline input shaft is worn or missing, see Novak's improved, hardened 23 spline input shaft in Related Products, below.
Jeep New Process 208, 219, 228 & 229 Transfer Cases
This kit does work with the FSJ New Process transfer cases as they have a similar interface with the Dana 300. Driveshaft clearance is not a problem with these units and they are plenty strong for these applications.
That said, we've been known to recommend replacing the older style FSJ New Process transfer cases (especially the tricky 219, 228 and 229) with a newer, more modern version such as the part-time 231J with HD SYE kit installed and upgrades as appropriate. If so, this adapter kit is the one you need. However, if your transfer case is in good condition, then move forward with the conversion.
Dana 300 Front Driveshaft to Transmission Pan Clearance
For the front driveshaft to clear the relatively wide 4L60E pan, the following installation steps are required:
- The engine must be installed offset to the driver's side as discussed on this page and in the instructions
- The installer must use the factory 1-1/4" front driveshaft diameter.
- The transfer case front output yoke and corresponding driveshaft yoke must be the factory, low-profile style
- The front axle should not be narrower than factory
There will be some situations where the front pan will interfere, despite these efforts, possibly on the last two years of the CJ's production run. For these installations, a notched front pan is available. See Related Products, below.
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. Our adapter is drilled for multiple clocking locations from near-factory (20 degrees down) to near-flat (3 degrees down). However, pan clearances and front axle width may inhibit the flatter options.
Compatible Jeeps
This conversion is compatible with all longer wheelbase (CJ7 93.4” or longer) or stretched Jeeps. The TH350 is the only real automatic option practical for CJ5 and other short wheelbase Jeeps.
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.
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.
Related Products
Installation Requirements
Tools
The automatic transmission takes more specialized tools, knowledge, gaskets, seals, and snap ring pliers, etc. Installation after the output shaft is in place requires normal mechanics hand tools.
Rear Mount Provision
This transfer case adapter's design features a modular mounting and support system and mounting base, ready to accept our industry standard urethane isolator mount, available for purchase below.
Placement
Transmission placement is largely determined by engine location. It is not necessary in typical conversions to change the engine position. Setting the powertrain to the proper factory or conversion pitch angle - usually tilted down ~5 degrees (3-7 acceptable) is recommended.
Engines & Engine Mounting
Novak engine mounts are available to ease the installation of your GM V6 or V8 engine. Novak has engines mounts for most Chevy, Buick and GM Gen III+ V8's.
Novak's engine mounts, feature vibration dampening, superior strength and useful adjustability - adjustable even after the engine is installed. The design, strength, and affordability of our mounts are second to none.
Engine placement in these Jeeps should consider the following points:
- Left-right offset location is similar to factory at ~1-1/4" to the driver's side
- Avoid installing the engine too low (axle clearance and other issues)
- Avoid installing the engine too high (transmission tunnel interference, etc.)
- Set your engine to 4-7 degrees of tilt rearwards, like the factory engine & powertrain
- It is usually best that Chevy and Gen III+ V8 engines install approximately 3" further forward, using the back of the engine block face as the datum
- When mocking up your engine installation location, pay special attention to radiator and fan clearance.
- Firewall modifications are not expected.
Since CJ Jeeps have higher hood clearance, clearance for classic Small Block and high Vortec (truck style) intakes and accessories is not a problem. Same for CJ's and Trucks that are getting these transmission / engine combos as retrofits.
Novak Gen III+ engine mounts for TJ, XJ, & '76-'86 CJs will remove any guesswork from the engine installation location as they are predetermined for the best location and engine clearance margins.
Driveshafts
Driveshaft length changes may be required. Chevy engines (with their rear distributors) can install around 3" further forward than AMC engines. It is also recommended that LS family engines be installed 3" further forward than the factory block (using the back face of the block as the datum point) for exhaust clearance, firewall access, etc.
Because of the engine placement and transfer case SYE kits are frequently installed with many of these conversions, you may end up with a longer rear driveshaft (very desirable for lifted Jeeps) and a shorter front driveshaft.
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.
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.
Strength Comparison of 27 vs 23 Spline Versions
The 27 and 23 spline shaft sizes are quite comparable in minor diameter (the diameter of the shaft at the root of the splines) and therefore, strength. Diameters are very close and the finer 27 spline vs the coarser 23 spline has shown no significant strength variation. The E4340 (similar to 300M) material used in production of the Novak shaft is of a superior strength both in PSI yield and torsional resistance - which is exactly the type of load these shafts see. Aside from that, fundamental design strengths are comparable.
GM 27 spline and Jeep / Dodge 23 spline shafts have a history of great strength in factory applications and Jeep aftermarket set-ups.
Output Shaft Strength
We’re avoiding the problem of a broken shaft like this one by going through the trouble and expense of making our output shafts from a solid bar of exceptionally strong E4340 (similar to 300M) alloy steel, instead of lower grade alloys or friction welding salvage GM shafts. A second, sometimes less obvious but pernicious problem is the issue of warpage during friction welding and heat treating - which cannot be corrected when the shaft journals are already ground and worn at or below factory specifications. Novak shafts receive a final grind of bearing journals after the heat treat process to ensure the ultimate finish. The Novak shaft is produced to factory specifications with stress risers removed. Our 4-axis CNC cut of spiral gear, oil feed passages and other features are no small tasks. This attention to detail, maximized strength through design and material along with precise tolerances provide the ultimate parts for your project.
Also See
- Complete 4L60E Transmission Package
- Parts for the Dana Model 300 Transfer Case
- Dana 300 Transfer Case Twin-Stick Shifter Kit
- Dana 300 Ultra-Short HD Rear Output Assembly
- The Novak Guide to the GM 4L60E Automatic Transmission
- The Novak Guide to the Dana Spicer Model 300 Transfer Case