Jeep Dana Models 18 & 20 Transfer Cases
Our SM465 to Dana Spicer 18 & 20 conversion is one of our most popular manual shift transmission conversion assemblies, combining the strength, refined design, broad engine compatibiliy and excellent gearing of the Muncie 465 four-speed transmission with two of the greatest transfer cases ever made.
*Note that we recommend you also purchase the transmission mainshaft bushings required when changing a 465 mainshaft, as discussed in Transmission Mainshaft Replacement, below.
At 1" in length, this kit is the shortest Muncie 465 adapter in the industry, providing a combined transmission and adapter length of only 13". Especially important for short wheelbase Jeeps, the Novak kit provides an excellent transmission conversion combination, reducing U-joint angles and driveline strain.
The adapter itself is cast and precision machined of a high-grade aluminum alloy featuring a heavy cross-section.
Any version of the SM465, including 2wd, 4wd early & 4wd late styles are compatible with this adapter assembly. There are no advantages between the 2wd vs. 4wd versions of this transmission.
Transfer Case Input Gear
Our transmission mainshaft is splined for either six-spline input gears, or ten-spline input gears.
Six-spline gears are predominately most common, as found with the Jeep T84, T90, T86, T89, T98, T18, T15 & T150. The rare ten-spline version is only availalble on the 1966 - 1974 transfer cases against the Jeep T14 transmission.
All Warn type overdrives are compatible with this conversion. Spline count information is the same.
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.
Transfer Case Bore Size
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.
Transmission Mainshaft Replacement
The SM465 transmission uses three sintered iron bushings that are pressed onto the transmission mainshaft gear journals. When changing a mainshaft, you or your transmission professional will replace these bushings. We also recommend our basic gasket & seal kit, or our all-inclusive master rebuild kit, depending on your assesment of your transmission's condition. See our SM465 parts page for information and to add these items to your conversion kit.
Transfer Case Strength and Condition
The Dana transfer cases are very well matched to the 465. They are uncommonly strong, compact and servicable. They are capable of power ranging up through V6s, V8s and even the Chevy Big Blocks.
It is not requisite that you rebuild your transfer case to successfully complete the conversion, but it may be a good time to do so if your transfer case leaks or has many miles of service. We've made our Dana 18 & 20 gaskets & seals kits and our all- inclusive master rebuild kits available for this purpose.
Engine Compatabilities & Engine Mounting
AMC Jeep engines are compatible with the GM SM465 transmission. See Adapting GM Transmissions to AMC Bellhousings. AMC (258, 4.0, etc.) engines may be left in the factory location in virtually all SM420 installations.
An SM465 installation is often done in conjunction with an engine conversion into the Jeep. These engines include the Chevrolet Small Block V6 & V8, from 1955-2006 or the Gen. III+ V8 and some other GM motors. Carbureted, TBI and TPI engines are all compatible with this transmission.
Engine Crank to Transmission Pilot Bushing
This transmission can be married to stock (i.e., AMC I6) as well as conversion (i.e., GM V6 / V8) engines, and a custom pilot bushing will be required in many instances. Some common choices with the SM465 transmission are listed below:
>Bushing, pilot, AMC cranks to the SM465
>Bushing, pilot, GM Gen. I-III (1955-2000) cranks to SM465
>Bushing, pilot, AMC cranks to the SM465
For pilot bushings not listed, see our full collection.
Transmission Rear Mount
This transfer case adapter's design features a threaded base that is ready to accept our industry standard urethane isolator mount, available for purchase (right). This is our strongest and preferred rear mount unit. Our #462R kits are designed for it, and its usage is essential to protect powertrain components from the flex and jar typical of any automobile, but especially Jeeps.
This mount will sit onto your stock cross member / skidpan, into which you will drill two attachment holes. You will find it to be a clean and simple process.
Transfer Case Shifter
This transmission conversion will allow for the retention of the factory Dana 18 twin-stick shifters, Dana 18 single-stick shifter, and many of the Dana 20 shifters. Some tube-mounted Dana 20 shifters may need to be modified, or replaced with this twin-stick shifter kit. Dana 18 shifter clearance on some versions may require some grinding of an SM465 gusset for clearance.
Use of the OEM style transmission shifter for the SM465 is easily done. The installer may opt to bend the stick to fit the particular Jeep application.
We can supply a new, straight stick with the revised, one-piece finger that replaces the looser (and occasionally worn or broken) two-piece factory design. This stick can be custom bent to the driver's preference.
Yoke & Driveshaft Clearance
Use of the factory size driveshaft and yoke is recommended, but there is room for larger units if desired. Our adapter design has maximized clearance between the transmission and yoke. No transmission modifications are required for clearance on this wise.
Driveshaft length changes are often required. However, some GM engine installations will allow for the transfer case to remain in its OEM location.
|As the SM465 is a popular option with GM conversions or AMC engines, consider our RadLock radiators for the best cooling available.|
Some of our customers, fearful at the perceived expense of new or modified driveshafts, attempt to let the existing driveshafts dictate engine, transmission and transfer case location, sometimes to the detriment of the project. Driveshaft modifications are usually inexpensive when performed by driveline, RV or tractor implement specialists. New driveshafts are an option but seldom a requirement in regards to the actual successful conversion. Jeeps that require extensive travel or specialty-built driveshafts have this option available through several fabricators across the nation.
Engines & Engine Mounting
An SM-465 installation is often done in conjunction with an engine conversion into the Jeep. These engines include the Chevrolet Small Block V6 & V8, from Generations I, II, & III, 1955-2006. Carbureted, TBI and TPI engines are all compatible with this transmission.
|Novak's MM Series engine mounts, featuring excellent vibration dampening, superior strength and impressive adjustability - adjustable even after the engine is installed.|
In any scenario, it is often preferable that the engine be installed (as the Jeep engines usually are) with an offset of 1" to 1-1/2" to the driver's side. Other engine mounts on the market - especially the bolt-in versions - do not take this into account and make other placement decisions for the installer that do not take the full powertrain into account. Novak offers what we have found to be the most intelligent engine mounting system for Jeeps available, allowing the installer to make an easy and satisfying decision as to powertrain placement with the SM-465 and the Dana 18 / 20 both considered.
The design and strength and affordability of our mounts are second to none.
AMC engines may be left in the factory location in virtually all 465 installations.
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.
|A view of a Model 18 transfer case joined to the SM 465 with the Novak #462R adapter assembly. This excellent arrangement makes these oustanding gearboxes uncannily appear as if they had been designed for each other. The Model 20 and most of its shifter configurations fit the SM 465 equally well.|