Dana 300 Transfer Case - Gearbox Anatomy

Here are the shift rails. The interlock resides inside the aluminum housing. Also note that this case uses the 26-spline output shafts (arrow).

Here are the shift rails. The interlock resides inside the aluminum housing. Also note tha

The Dana 300 has exceptional strength for its size. Worthy believes that a stock Dana 300 can easily handle power ratings up to 350 horsepower and 350 lb-ft of torque, while Novak says they regularly see them handling big-block power and deep compound gearing without failure. Novak also reminds us that the Dana 300 was used successfully in the Jeep J-4000 1-ton trucks. Breakage usually occurs because of shock loads to the drivetrain from an aggressive driver, a worn intermediate shaft, or worn bearings.

If there are any drawbacks to the Dana 300, it would have to be the standard 2.0:1 low-range gear ratio and the fact that the centered rear output shaft does not allow it to be clocked for improved ground clearance and driveline angles the way a Dana 18 can be with its offset output. Also, the Dana 300 gears are unbalanced, and Novak says that while it is rare, breakage could occur because the helical front seat can produce significant side loads against the case.

With the endplate removed from the front output shaft, the bearing is visible. The endplate uses shims to adjust the preload on the front output.

With the endplate removed from the front output shaft, the bearing is visible. The endplat

Mel Wade at Off Road Evolution in Fullerton, California, had an old Dana 300 in his shop and offered it up as the sacrificial lamb for this story so that we could get a better look at its internals. We headed down to Fullerton, where we plucked an old Dana 300 out of the junkpile and let it die a hero.

Also be sure to check out the excellent history, parts, and rebuild guides available at www.novak-adapt.com.

Model 300 in Popular Production Vehicles
Ford
1966-'77 Broncos
General Motors
1969-'73 Blazers (some)
International
1965-'79 Scout
Jeep
1962-'79 Fullsize J-series
1967-'73 C101 and C104 Commando
1972-'79 CJ-5, CJ-6, and CJ-7

With the case flipped over and the inspection cover removed, you have a better idea of how all the gears fit together. Novak offers a billet cover that replaces the flimsy and leak-prone stock piece and increases oil capacity. This is a must-have upgrade.

With the case flipped over and the inspection cover removed, you have a better idea of how

Dana 300 Quick Hits
Ford
Similar to Jeep, but used a left-side front output shaft and/or a lower 2.46:1 (or 2.34:1) low range.
General Motors
Not as common as the NP203 or NP205 and only used with three speed manual transmission.
International
Had twin sticks from the factory up to '69.
Jeep
Avoid the problematic remote style "J"-shift versions.