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 compatibility, and excellent gearing of the GM Muncie 465 four-speed transmission with two of the great Jeep transfer cases.
This compact Muncie 465 adapter provides a combined transmission and adapter length of only 13". The adapter itself is machined from T6 aluminum alloy, featuring a heavy cross-section.
This transfer case adapter's has an integrated mount base, ready to accept our industry standard urethane isolator mount, available for purchase below.
The Novak-manufactured 6 or 10 spline option output shaft is machined from premium alloy steel, heat-treated for hardness and strength and ready for installation into the SM465 transmission and then the D18 or D20 input gear attaches directly to it, using the terrific strength of the SM465 rear main bearing for support.
The kit contains aluminum adapter housing, transmission output shaft, seal, transfer case to adapter gasket, transmission to adapter gasket, fastening hardware, steel mounting base, and instructions.
Any version of the SM465, including 2wd, 4wd early, and 4wd late styles are compatible with this adapter assembly. For the purposes of this conversion, there are no disadvantages between the 2wd vs. 4wd versions of this transmission.
Mainshaft replacement is largely straightforward. Good work is within 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 installers consider one of our complete Novak remanufactured and upgraded transmission packages. These professionally-built transmissions are stress-tested, delivered to your door and ready to bolt in.
All Jeep models of the Dana Spicer 18 and Dana Spicer 20 transfer cases are compatible with this adapter assembly. IH versions of these transfer cases are also compatible. The correct input bore and spline count must be observed. This adapter is not suitable for the Ford Bronco transfer case as it is of an entirely different design in attachment and drop.
Our adapter shaft is splined for six spline input gears.
Consult our informative Dana gears interchange chart if necessary.
All Warn and Saturn type overdrives are compatible with this conversion as long as the spline count is correct. We do not have replacement gears for the overdrive version.
The diameter of the transfer case center input locating bore will be either 3-5/32" or 4".
This combination is compatible with most Jeeps as this is one of our shortest four-speed combinations. Some shift tunnel modifications may be needed due to the increased size of the transmission, but can be cleanly done.
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. A procedure adapting to the Jeep engines is shown here.
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.
A pilot bushing is always required for installation choose the correct version for your application from these choices
Though complete disassembly of your transmission is not required, it is our recommendation to rebuild and update a tired or unknown unit. These rebuild kits offer the best available components, bearings, synchros, gaskets, and seals to perform a first rate rebuild along with your installation. Our instructions accompany all rebuild kits. At the very least, you will want the gaskets and bushing set but we do recommend the full rebuild kit.
If your transmission has a tendency to jump out of 3rd gear or its history is unknown, this is the updated fix. All of our transmissions feature this upgrade.
This kit contains the three press-on mainshaft bushings that are almost always destroyed when removed from the original shaft. These are included in our Master Rebuild Kit, or available separately here.
Straight sticks are available if yours is work or you simply want to start with a clean slate to get the bends right.
Often damaged or just needing a more rigid piece for better leak resistance, this piece will help with solving both.
These billet aluminum, anodized billet covers seal up substantially better than the factory stamped steel covers. Check your transmission to see if it requires one or two of them.
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.
Gasket and seals kit
Dana 20 Billet Pan and PTO Cover
These rigid and precisely machined billet bottom pans are a big step in getting your Dana transfer case sealed up. The thick, smooth-finished flange replaces the thin, warped factory pans and they virtually assure a drip-free seal. They also add structural rigidity to the overall transfer case.
The transmission shaft installation takes more specialized tools, heavy snap ring pliers, a press to remove and replace bearings, etc. Normal mechanics tools are required for the balance of the installation.
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 a twin-stick shifter kit. Dana 18 shifter clearance on some versions may require some grinding of an SM465 gusset for clearance.
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.
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.
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.