Adapting the

Turbo Hydramatic 350

to the

Jeep Dana Model 300 & FSJ NP Transfer Cases

TH-350 to Dana 300

Our TH350 to Dana 300 conversion makes for a strong, and capable assembly both on-road and off-road. It is one of the more popular automatic transmission conversions into Jeeps, providing a compact geartrain and compatibility with a variety of engines.

Novak Transfer Case Adapter

The adapter is compact at only 3.1" long for a combined transmission and adapter length of 24.8". The adapter itself is precision-machined from aluminum, featuring thick flanges, a heavy cross-section and superior strength. 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.

Any version (2wd, 4wd, etc) TH350 can be made to be compatible.

There are a few options and kit versions to be aware of.

Option I: Transfer Case Input Shaft Version

TH350 to Dana 300 Adapter Kit

Kit 135, adapting TH350 transmissions (4wd style) to the Jeep Dana 300 transfer case

Kit contents:

  • Adapter housing
  • Transfer case input shaft, 27 splines
  • Seal
  • Gasket
  • Seal ring
  • Fastening hardware
  • Steel base mount foot
  • Instructions

4wd styles of the TH350 are ideal for this version of our kit, which comes with a new 27 spline input shaft for your Dana 300 transfer case. Transmission disassembly is therefore not necessary for this scenario. Partial disassembly of the Dana 300 input shaft assembly is required and instuctions are included. If you would like a pre-built input assembly that is pressed together and ready, see our #300ISK kit in Related Products, below.

TH350 4wd shaft stickout length
The 4wd version of the TH350 will have a ~3/4" output shaft stickout length.

Some customers choose this as a time to do a master rebuild of the Dana 300, for which we offer the elite kit. See Related Products, below.

Extended input shaft installed in Dana 300

Option II: Transmission Output Shaft Version

Adapter kit for the TH-350 to Jeep transfer cases

Kit 135-S, adapting TH350 transmissions (2wd version) to the Jeep Dana 300 or Jeep NP208, 219, 228 or 229 transfer cases

Kit contents:

  • Adapter housing
  • Transmission output shafts, 23 splines
  • Seal
  • Gasket
  • Seal ring
  • Fastening hardware
  • Steel base mount foot
  • Instructions

The #135-S adapter is compatible with all versions of the TH700R4. This may be your kit if...

  • you have a 2wd TH350
  • you have a 4wd TH350 but it needs a rebuild anyway
  • you have a New Process FSJ transfer case - this is the only compatible option
  • you are unsure of which version of the transmission you'll have at the time of rebuild
  • your transfer case was recently rebuilt and you don't want to open it back up

The new 23 spline TH350 output shaft is machined from 300M alloy steel which provides a substantial strength upgrade. The new Novak shaft splines directly into the OEM style input shaft of Dana 300 or FSJ NP transfer cases. This requires disassembly of the transmission, and we recommend the services of a transmission professional.

Some customers request our complete Novak remanufactured and upgraded transmission packages. This master-built, professionally prepared transmission is constructed to your specifications, tested, delivered and ready to lift into your Jeep.

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 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.

Applications & Compatibility

Compatible Transmissions

TH350 with Novak Adapter

All versions and years of the TH350 can be adapted to the Dana 300. Chevrolet, Buick / Oldsmobile / Pontiac and Unicase versions all work equally well with the correct adapter option.

Jeeps

This conversion is compatible with all Jeeps. The TH350 is the only real automatic option practical for CJ5 and other short wheelbase Jeeps. you may consider our #133 Short version adapter kit and possibly shorter transfer case output shafts to further facilitate longer rear driveshafts in those applications.

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 TH350 should stock strength come into question.

Compatible Engines

Any engine that can be made to work with the TH350 will work with this adapter. Natively compatible engines such as the Small Block Chevy, Chevy V6, Big Block Chevy, and even the 1997-2006 Vortec / LS / Gen III+ engines popular choices. However, be aware of engine crank spacing issues with Gen III+ engines when used against Gen I transmissions such as the TH350.

AMC engines can be adapted via a front adapter such as our 437 series kits.

Related Products


Urethane Rear Mount for Crossmember
Auto transmission cooler
Dana 300 Rebuild Kit
Billet aluminum Dana transfer case pan
Dana 300 rear bearing cap
Dana 300 Input Retainer Assembly
Dana 300 Super Short Tailhousing
Dana 300 Exended Spline Input Shaft
Dana 300 twin stick shifter
Twin Stick Boot
1976-1986 Jeep floor tunnel cover
TurnKey TH350 Transmission Package

Installation Requirements

Tools

TH350 adapter view with shifters

Tools required will vary depending on which kit is selected. The automatic transmission takes more specialized tools and knowledge,gaskets, seals and snap ring pliers, etc. The D300 input will require bearings be pulled and pressed on the input, in additionto typical mechanic's hand tools.

The automatic transmission takes more specialized tools, knowledge, gaskets, seals and snap ring pliers, etc. Transfer case input installation takes normal tools along with some larger snapring pliers. Installation after the output shaft or input gear isin place requires normal mechanics tools.

Powertrain Placement

As these usually are installed as part of an engine swap setting the powertrain to the proper pitch angle is recommended - usually tilted down ~5 (3-7 acceptable) degrees. Offset will be to the right (passengers’) side because of the driver drop transfer case and front differential (usually 1 to 1-1/2”). 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

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.

GM Engine Mounts for JeepsNovak engine mounts are available to ease the installation of your engine.

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.

Novak Gen III+ engine mounts for 1976-1986 Jeep CJ models will remove any guesswork from the engine installation location as they are predetermined for the best location and engine clearance margins.

Driveshafts

TH350 transmission, adapter, Dana 300 transfer case

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.

SR4, T4, T5 Replacement?

Installers should note a possible benefit of the TH350 - usually done in conjunction with a Chevy Small Block engine conversion - of possibly not having to change or modify driveshafts in some 1980-1986 CJ Jeeps. The TH350/Novak adapter combo is about 1" longer than the stockSR4,T4, T5 transmissions. However, most Chevrolet engines install 1 or more inches ahead in the engine bay, offsetting that difference.

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 bechosen for reasons external to this transmission upgrade.>

Also See