Our TH700R4 to Dana 300 or FSJ NP transfer cases conversion makes for a strong, and capable assembly both on-road and off-road, and it remains one of our most requested automatic transmission to transfer case combinations.
The adapter is compact at only 3.1" long for a combined transmission and adapter length of 26.5". The adapter itself is precision machined aluminum, featuring thick flanges, a heavy cross-section and superior strength. It is drilled for multiple clocking locations from near-factory (20 degrees down) to near-flat (3 degrees down). However, pan clearances, body tunnel clearance and front axle width may inhibit the flatter options.
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.
There are a few options and kit versions to be aware of.
The 137-A adapter is compatible with all versions of the TH700R4. This may be your kit if...
The new 23 spline TH700R4 output shaft is machined from E4340 (similar to 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.
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.
4wd styles of the 700R4 / 4L60 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.
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.
If you've got a good New Process chain drive transfer case in your 1980-1991 FSJ Jeep, you may want to retain it with your conversion. This Novak kit comes with a new 27 spline input gear for your transfer case, and will spline directly to the 4wd output shaft of the 700R4 / 4L60 / 4L60-E transmission. This will require disassembly, install, and reassembly of your transfer case.
Any version and year of the TH700R-4 can be adapted to the 300 transfer case, including "90 degree" (Gen. I, II, III V6 & V8 Small Block or Big Block engines) and "60 degree" (early S10 Blazer 2.8L engine style) versions of the 700, as determined by your choice of engine.
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.
This conversion is compatible with all longer wheelbase or stretched Jeeps. The TH350 is the only real automatic option practical for CJ5 and other short wheelbase Jeeps.
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 TH700R4 should stock strength come into question.
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.
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.
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.
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.
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:
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.
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.
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.