Adapting the

GM Muncie SM465

to the

Jeep Dana Models 18 & 20 Transfer Cases

Adapter kit for SM465 to Jeep Dana 18 & 20 transfer cases

Kit 462R, adapting SM465 transmissions to Jeep & IH Dana 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 compatibility, and the 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.

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 adapter has an integrated mount foot to which you will attach a urethane isolator mount.

Kit Contents

  • Adapter
  • Transmission mainshaft, 6 or 10 spline
  • Seal
  • Gaskets
  • Fasteners
  • Shims
  • Loctite
  • Instructions

Applications & Compatibility

Transmission Versions

SM465 Side View, with adapterAny 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.

Transfer Case Versions

SM465 with Dana 18 PTO DetailJeep 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.

Transfer Case Input Gear

dana_18_20_input_gearOur adapter shaft is splined for six spline input gears.

  • Six-spline gears (shown, right) are most common and usually found behind Jeep T84, T90, T86, T89, T98, T18, T15 & T150.
  • The ten-spline version was only available on the 1966 - 1974 transfer cases against the Jeep T14 transmission
  • 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.

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.


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.

Compatible Jeeps

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.

Compatible Engines

Any engine that can be made to work with the SM465 will work with this conversion. They include:

Rear Mount Provision

SM465 in an early JeepThis transfer case adapter's has an integrated mount base, ready to accept our industry standard urethane isolator mount, available for purchase below.

Related Products

Urethane Rear Mount for Crossmember
Pilot bushings
SM465 mainshaft journal bushing kit
SM465 Gaskets Kit
SM465 transmission parts
SM465 transmission parts
Shifter Retention Kit, SM420, SM465, T176, NP435
Shifter stick for SM465
Shifter stick for SM465
Shifter stick for SM465
Shifter stick for SM465
SM465 Countershaft Billet Front Cover
Billet PTO Cover
1976-1986 Jeep floor tunnel cover
Billet aluminum Dana transfer case pan
Dana 18 & 20 Rebuild Kit
Dana 18 & 20 Input Gears
Turn-Key SM465

Installation Requirements

SM465 & Dana 20 with Twin Stick Shifters


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.

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 a twin-stick shifter kit. Dana 18 shifter clearance on some versions may require some grinding of an SM465 gusset for clearance.

Engines & Engine Mounting

GM Engine Mounts for Jeeps

Factory engine placement on CJ Jeeps is excellent for the SM465 transmission, whether using an AMC I6 or V8 engine. If installing an AMC or GM V8, your engine mounts should permit about a 1-1/4" offset towards the driver's side. Novak's engine mounts, feature vibration dampening, superior strength.


Driveshaft length changes are often required. Some 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.

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.

Also See

SM465 with a Dana 18