Adapting the
Dana Spicer Models 18 & 20 Transfer Cases
to
Divorced Mount Transmissions

Dana Transfer Case Bore Diameter Select Bore Diameter 3-5/32", most Dana 18's 4", late Dana 18's & all Dana 20's

320-3;320-4

Kit Contents:

• Adapter housing
• Adapter shaft, 6 spline Dana input
• Bearings
• Gasket
• Yoke, 1310
• Fasteners
• Instructions

This kit is preassembled for you.

Our divorced mount Dana 18 & Dana 20 conversion permits the use of a variety of different transmission applications and vehicle platforms.

The Novak divorced mount adapter is 5.75" long, as measured from the transfer case face to the center of the universal joint. The adapter itself is cast and machined high-grade aluminum alloy, featuring a strong flange and generous cross-section. The adapter shaft is machined from triple-alloy gear steel mounted in twin bearings to sustain moment loading from the forces of the transfer case helical, involute input gear.

We strongly recommend our urethane rear mount #RMU in Related Products, below. It is strong, versatile, and can be configured with your crossmember solution. See Related Products, below and remember that hard mounting is never an appropriate option and will void any adapter warranty.

Applications & Compatibility

Transmission Versions

Any transmission you deem appropriate for your project is compatible. We provide a 1310 input yoke to which you will connect a jackshaft from your transmission output.

Transfer Case Versions

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.

Transfer Case Input Gear

Our 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.

Related Products

Jeep Rear Transmission Mount (Polyurethane, Novak Style)

This rear mount bolts direct to your Novak adapter, and can be used with a variety of crossmember styles.

RMU

Gaskets & Seals Kit, Dana 18 & 20 Transfer Cases, #GS18

Installers frequently replace gaskets and seals when working with these transfer cases. These gaskets are also found in our Dana 18 or 20 master rebuild kit, seen here with our Dana 18 parts, or here with our Dana 20 parts.

Jeep Dana Transfer Case Billet Bottom Cover Pan, Deep

A deep and rigid billet aluminum pan for your Dana 300 transfer case. More fluid capacity, better sealing and some anodized eye candy for your geartrain. Shallow version for better ground clearance also available here.

D328-D

Dana 20 Front Output Rear Bearing Billet Cap

Seal up and shim you front output shaft rear bearing from the inside with this innovative bearing cap assembly. The anodized cap, shims and o-ring sealed bolts are included.

933725-K

Dana Transfer Case Input Gears

Both 6 & 10 spline versions of this kit are available, but if your transfer case is missing its input gear, they are available here.

Installation Requirements

Assembly of this kit is can be straightforward. However, overall fabrication, mounting and layout considerations may make a divorced mount conversion a more advanced project.

Clocking Information & Driveshaft Clearance

The Novak adapter maintains factory clocking of your transfer case.

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. This aspect will depend largely on your installation.

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.

Driveshafts

Driveshaft length changes will be required, as this geartrain combination is longer than most factory Jeep combinations. However, since the transfer case can be divorced mounted, the driveshaft angle can be shared and mitigated between the jackshaft and the rear driveshaft.

Axles

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

• Parts for the Dana Model 18 Transfer Case
• Parts for the Dana Model 20 Transfer Case
• Dana 20 Transfer Case Twin-Stick Shifter Kits
• The Novak Guide to the Dana Spicer Model 18 Transfer Case
• The Novak Guide to the Dana Spicer Model 20 Transfer Case