Adapting the GM 4L80-E Transmission

to the

Jeep Dana 300 Transfer Case & FSJ NP Transfer Cases

Novak's 4L80E transmission to the Jeep Dana 300 or Early New Process (or New Venture) transfer cases conversion makes for one of the strongest geartrains possible for both on-road and off-road, and has become an increasingly popular transmission to transfer case combination.

Product & Features


The Adapter 

The Novak 4L80 to Jeep transfer cases adapter is compact at only 3.0" long for a combined transmission and adapter length of 29-1/4" (equivalent to a ~22-5/8" manual transmission). The adapter itself is machined of a 6061 billet aluminum alloy, featuring thick flanges and a heavy cross-section.


Billet adapter housing, transfer case input or transmission output depending on kit selection, seal, transfer case to adapter gasket, transmission to adapter sealing ring, fastening hardware, steel mounting base, and instructions.



Applications & Compatibility


All versions and years of the 4L80E can be adapted to the Dana 300 and NP (New Process) transfer cases. 2 or 4WD versions all work equally well with the correct adapter option.

Output Shaft Speed Sensor

1991-1996 4L80E's should feature a speed sensor at the driver's side rear portion of the case (see image, below), whether they are 2wd or 4wd applications. 1997 and later 4wd applications often omit the rear sensor as this data is available from the transfer case output shaft in factory applications. This adaptation requires that this sensor and its internal reluctor ring be installed by a transmission building professional for proper operation. 

Option I: Transmission Output Shaft Version

The 4L83-A adapter is compatible with all versions of the 4L80E. This kit is typically best if:

  • you have a 2wd or 4wd 4L80E that is undergoing a rebuild anyway
  • you are unsure what 4L80E you have (or will have at the time of the conversion)
  • you are missing and need to install the rear speed sensor
  • your D300 was just rebuilt (doesn’t leak) and you’d rather not open it back up


This kit comes with a new 23 spline 4L80E output shaft that splines directly into the OEM style input shaft of a 300 transfer case. This requires disassembly of the transmission, and we recommend the services of a transmission professional.

The basic installation is a 2-2.5 hour bench job and will include at least simple gasket and seal replacements. Be sure that if your transmission is missing the output speed sensor it is added at this time, see below for the correct parts. This is a good time for a more thorough master rebuild and update of the Hydra-Matic. Many consider one of our complete Novak remanufactured and upgraded transmission packages. The advantage of a superior, professionally built transmission, tested and ready to bolt in delivered to you is definitely worthy of consideration.

The E & L designate early or late as described below. Please choose the correct version if using an output shaft replacement adapter.

Early vs Late 4L80E Oiling

In about 1997, GM changed the way the rear bushing is oiled in the 4L80E transmission. The shafts are not interchangeable and you will need to identify for sure which version you need.

  • The first design has two lube holes in the sides of the case bushing journal. Lube flows through these feeding the output shaft and forward to the planets.
  • The second design does not have the lube holes instead has a tube feeding oil from the valve body. 


Option II: Dana 300 Transfer Case Input Shaft Version

One 4wd version of the 4L80E is ready to bolt up to our 4L83 adapter kit. Disassembly of the transmission is unnecessary as the 32 spline 4wd style output shaft which protrudes about 3" from the rear face of the 4L80E transmission main case is correct for this kit version. Partial disassembly of the transfer case is necessary to install a new matching 32 spline Dana 300 input shaft machined from triple-alloy gear steel which provides a superior upgrade.

The input shaft installation is a 1-2 hour bench job and usually includes either a simple gasket and seal replacement or preferably a full rebuild of a tired D300. Bearings and pre-load are involved with this job. It is not requisite that you rebuild your Dana 300 to successfully complete the conversion. However, it is certainly worth consideration especially if your transfer case leaks or has many years of service. Our superior quality Dana 300 gaskets & seals kits and our all-inclusive master rebuild kits with stronger Novak manufactured center pin are highly recommended for this purpose. 

Option III: FSJ New Process Transfer Case Input Shaft Version

One 4wd version of the 4L80E is ready to bolt up to our 4L83 adapter kit. Disassembly of the transmission is unnecessary as the 32 spline 4wd style output shaft which protrudes about 3" from the rear face of the 4L80E transmission main case is correct for this kit version. Partial disassembly of the transfer case is necessary to install a new matching 32 spline NP208, NP219, etc input gear.

The input gear installation is a 2-3 hour bench job and usually includes either a simple gasket and seal replacement or preferably a full rebuild of a tired transfer case

Jeep New Process 208, 219, 228 & 229 Transfer Cases

We've been known to recommend replacing the older style FSJ New Process transfer cases (especially the troublesome 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. 

However, if your transfer case is in good condition, then move forward with the conversion.


Drivetrain Length & Compatible Jeeps

Because this is a longer transmission, it is not compatible with most short wheelbase Jeeps if they have much lift, due to driveshaft angles. CJ7's may be feasible if the lift is mild. Because these Jeeps can be relatively light and the GM 4L60E transmission can be very strong, it will usually be a more appropriate choice over the 4L80.

However, CJ8 Scrambler Jeeps, other longer Jeeps, especially the full sized trucks and Wagoneers, are ideal candidates if punishing transmission duty is a prime consideration.


We recommend the 4L80E be paired with the engine it originally came with - typically a Gen II GM V8 or most commonly, the GM Vortec Series (LS) truck engines. As the transmission is electronically controlled in conjunctino with the engine, these are best as a matched set. 

Related Products

Transmission Rear Mount

This transfer case adapter's design has a structural base for an industry standard urethane isolator mount, available for purchase. This is our preferred rear mount unit. Our kits are designed for it, and its usage is essential to protect powertrain components from the flex and movement typical of any automobile, but especially Jeeps.

Whether you are assembling onto a stock crossmember/skidplate or if you are setting up a high-clearance skid plate, you will find it to be a clean and simple process.


4L80E rear speed sensor retrofit kit


D300 Transfer Case Shifter

The stock D300 shifter may be used, possibly requiring minor modifications. Often it is advantageous to use a new twin stick style shifter, especially if you are able to remove the interlock pins during the transfer case rebuild process. For the Jeep Dana 300, we recommend two twin stick shifters. One features an adjustable length.


Another great option for the D300 is our Dana 300 Transfer Case Twin-Stick Shifter Kit which is a solid, high quality option but lacks the forward adjustability of the transfer case shifters. It has the option of billet knobs showing the engraved shift pattern.



All would require the



Transmission Tunnel Cover

Because the transmission and transfer case shifters are often in a different location than factory in these Jeeps, this new transmission tunnel cover gives the installer a clean slate. There are no screw holes nor transmission & transfer case shifter holes, allowing the installer to drill and cut them as necessary. An easy way to get a perfect fit is to use the old cover as a template, making cuts as necessary, then overlay on the new aluminum piece for perfect holes.

The finish is natural brushed aluminum, which looks pretty terrific, but it can easily be primed and painted to suit, if desired.

This tunnel cover is compatible only with 1976-1986 CJ Jeeps.



D300 Rebuild and Gasket Options


Gasket and Seals Kit

Dana 300 Billet Bottom Cover Pan


These rigid and precisely machined billet bottom pans are the answer to a few Dana transfer case dilemmas. The thick, smooth-finished flange replaces the thin, warped factory pans and they virtually assure a drip-free seal.

Two designs are available for the Dana 300: The shallower depth, low-profile version for Jeeps requiring greater ground clearance. This version increases fluid capacity over the factory pan by about 6 oz. The extended depth version that maximizes the fluid capacity for the most punishing service. This version increases fluid capacity over the factory pan by about 16 oz.


 Dana 300 Ultra-Short HD Rear Output Assembly

If you can accommodate the electronic speedometer or don’t need a speedometer option, this kit will give you the ultimate in strength and short length. Full details are here.


Transmission Cooling

Transmission Cooling is critical to the life of all automatic transmissions. Conventional in the radiator tank coolers are simply not adequate for long life on a Jeep’s transmission. Here are the products we recommend for best performance and ease of installation.



 D300 23 Spline Input Shaft

If your input is worn or you would like a new input shaft with longer spline engagement to match your Novak output this part is an excellent choice.


208 Rebuild Kit and Chain


Installation Requirements


Tools required will vary depending on which kit is selected. The automatic transmission takes more specialized tools and knowledge, gaskets, seals, snap ring pliers, etc. The D300 input will require bearings be pulled and pressed on the input, in addition to typical mechanic's hand tools. The 208 requires hand tools, large snap ring pliers and RTV to reseal. Rebuilds are a little more involved, but not much.


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. If you are installing against a factory AMC engine with our 437-AMC adapter kit, your factory engine should already have this proper offset. 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. 

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. 


Novak's engine mounts, featuring excellent vibration dampening, superior strength and impressive adjustability - adjustable even after the engine is installed. The design, 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.


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. 


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.

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