NP203 New Process Transfer Case Diagram

The New Process 203 was used in GM, Ford, and Dodge through the 70's behind auto and manual transmissions. They were originally a full time 4wd 'case, meaning all 4 tires receive power at all times. This was made possible through use of a differential in the back of the 203 that let the front and rear drive shafts turn at different speeds as just as a diff in an axle lets each axle shaft turn at a different speed. For off road use, the 203 had a "lock" position in which the differential was locked making the front and rear outputs spin at the same speed. Shift positions are: High, Lo, High Lock, Low Lock and Neutral.

A popular modification to the 203 was to install a "part time" kit to eliminate the differential. In this configuration the 203 operates like more conventional transfer cases in that it's either in 2wd or 4wd and when in 4wd the power is evenly split from front to rear.

The NP203 is identified by several features.

• The transfer case is made up of 4 sections bolted together, a range box, the chain case which houses the chain drive to the front driveshaft output, the differential housing, and the output housing. The front 2 sections are cast iron, the back 2 sections are typically aluminum.

• The overall length is about 22-23" from the face of the case to the rear output yoke centerline.

• The shifter is a somewhat complicated box that actuates the 2 levers on a single shaft on the side of the range box section of the 203.

• The model tag (if it still exists) will be found on the front of the chain case above the front output shaft. It will list the model number, the manufacture date and the gear ratio.

Exploded View Diagrams of the NP203 Transfercase  (click to enlarge)

NP203 Resources:

NP203 + NP205 Transfercases Np203+np205 transfer cases by Gordon Pritchard and bc4x4.com.
How to Fix Up the NP203 Transfer Case Pertersons 4Wheel & Off-Road details how to rebuild the full-time four-wheel-drive NP203 transfer case. Transfer Cases Doubler NP203 / NP205 Adaptor The NorthWest FabWorks Adaptor kit allows you to mate the reduction box portion of a NP203 transfer case to the stout NP205.	NP203 Transfer Case Data Sheet NP203 based "Doubler” systems Example of a "Doubler" system: NP203 reduction unit mated to an NP205 New Process 203 Transfer Case Tech