• The Dana Spicer Model 20 is a heavy-duty transfer case. It was used on trucks from various manufacturers, in the late 1960s through the late 1970s.
  
  Novak Conversions calls the Dana 20 "one of the strongest and most refined of all the popular transfer cases.... compact, light, durable, simple to build and capable."
  
  

Construction

• The Dana 20 is made of cast iron, and has a deep oil pan. It has a "Texas-shaped" front mounting input flange. It bolts to the transmission using five three-eighth-inch bolts.
  
  The front driveshaft output is on the passenger side. Its centered rear output housing allowed for efficient, quiet direct drive in two-wheel drive, according to Novak Conversions.
  
  It has a cast iron tail housing, in comparison with other popular Dana transfer cases which use aluminum. It is between 10 and 11 inches long.
  
  

Model Lines

• General Motors trucks, Jeep vehicles, and International Harvester vehicles used the Dana 20 Gear.
  
  The FSG Wagoneer and J100 Gladiator were some of the Jeep Motors vehicles which used the Dana 20. Also using the Dana 20 were the 1962 to 1979 full-size J-series Jeeps, 1967 to 1973 C101 and C104 Commandos, and 1972 to 1979 CJ5, CJ6 and CJ7.
  
  The Jeep J4000 is a one-ton truck that used the Dana 20. It was said to be very reliable in this heavy-duty vehicle.
  
  Chevrolet outfitted some 1969 to 1973 Chevy Blazers with the Dana 20. Ford's Bronco full-size SUV also used the Dana 20 from 1966 to 1977.
  
  The Dana 20 was paired with Jeep transmissions including the T98, T18, T14, T5, T150 and TH400.
  
  

Features

• The Dana 20 is a heavy-duty transfer case that allows two-wheel and four-wheel drive, in high and low ranges. The low range gear ratio is 2.03-to-1. In high, the ratio is 1-to-1.
  
  

Variations

• The Jeep, IH, Chevrolet and Ford versions are each slightly different and might not be interchangeable without modifications.
  
  Ford's Bronco transfer case had a 2.46-to-1 low gear and a driver's side front output shaft. After 1973, the gearing ratio of the Ford Dana 20 was 2.34-to-1. The 1966 to 1972 Bronco Dana 20 used a single shift rod and shifted in a straight line pattern, "4 Hi - 2 Hi - N - 4 L," according to HighImpact.net. The 1973 to 1977 Bronco Dana 20 used a "J" pattern shifter.
  
  Changing the Bronco Data 20 to a twin-stick shifter is a common modification. This allows the driver to select front-wheel, rear-wheel or four-wheel drive in either range. It is an easier conversion on the 1973 to 1977 Broncos than on the earlier models.
  
  A variation named the Dana 21 was paired with automatic transmissions. This variation had a single speed.