Adapting SM465 transmissions (all versions) to Jeep Model 300 & FSJ transfer cases, 23 spline mainshaft
Adapting the GM Muncie SM465 to the Jeep Dana Model 300 Transfer Case
Our SM465 to Dana 300 conversion makes for a very refined, expansively geared, and extremely durable assembly both on-road and off-road. It has become one of our most popular manual shift transmission conversions into Jeeps, providing a compact geartrain, a very low crawling gear, compatibility with excellent engines, and ease of installation.
Product & Features
The Adapter
The Novak SM465 to Jeep Model 300 transfer case adapter is very compact at only 3.2″ long for a combined transmission and adapter length of 15.2″. The adapter itself is cast and machined of 356T6 aluminum heat treated alloy, featuring thick flanges, a heavy cross-section, and strength-adding gussets.
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.
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.
The new Novak manufactured 23 spline output shaft is machined from premium alloy steel and hardened for maximum strength and longevity ready to be installed in your Borg-Warner transmission and then spline directly into the D300 or with the input version of the kit it will spline on to the short 10 spline output of your SM465.
Contents
The kit contains aluminum adapter housing, transmission output shaft or transfer case input shaft, seal, transfer case to adapter gasket, transmission to adapter gasket, fastening hardware, steel mounting base, and instructions.
Applications & Compatibility
Output Shaft Version “23”
Transmissions
Any version of the SM465, including 2wd, 4wd early, and 4wd late styles are compatible with this adapter assembly. There are no advantages between the 2wd vs. 4wd versions of this transmission.
Mainshaft replacement is largely straightforward. Good work is within easy reach of the careful home mechanic and instructions are included. We recommend at least our basic gasket & seal kit and the SM465 the main shaft bushing set. Better yet, this is a good time for a more thorough master rebuild and update of the transmission. 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.
Transfer Case
All Jeep Dana 300 (and FSJ New Process) transfer case input shafts / gears feature 23 splines. Our included Mainshaft will spline in directly to these input shafts with no transfer case modifications required.
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.
Input Shaft Version “10”
Transmissions
Only the short 10 spline SM465 early 4wd style transmission output is compatible with this adapter assembly. Disassembly of the transmission is unnecessary as the 10 spline 4wd style output shaft is correct for this kit version. Partial disassembly of the transfer case is necessary to install a new matching 10 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. 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.
Jeeps
Compatible with most Jeeps that originally featured the D300 transfer case. If you are retrofitting both, keep in mind length and shifter location to ensure clearance for both.
Engines
Any engine that can be made to work with the chosen transmission will work with this adapter. We have available parts to adapt several versions to various engines. See the SM465 information page linked below for that discussion.
