Transfer Case ID Guide
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 driveshafts turn
at different speeds as just as a diff in an axle lets each
axleshaft 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:
1. The transfer case is made up of 4 sections bolted together, a
range box (the gear reduction we use for the Doubler kit), 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
2. The overall length is about 22-23" from the face of the case
to the rear output yoke centerline.
3. 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
4. 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.
The New Process 205 was also used extensively
in GM, Ford, and Dodge. GM and Dodge used the 205 in some
trucks into the early 90's, Ford stopped using the 205 in 1979.
The 205 is a part time 4WD 'case, meaning when it's in 2WD the
front driveshaft will not receive power. It has 4 stock
shift positions, 2wd Hi, 4WD Hi, Neutral, and 4WD Lo.
had several different configurations with Ford and Dodge using
both married and divorced models and GM using many different
input spline types and 2 different bolt patterns.
The NP205 is identified by several features:
1. The transfer case is one piece of cast iron. There is a
short bearing retainer/output housing at the tail of the case,
and aluminum bearing retainers/seal retainers at the front and
rear outputs but the working parts are all in a single iron
2. There is a small idler shaft cover on the back of the 205
with 3 small bolts holding it on. This is somewhat unique
among transfer cases.
3. The overall length of the NP205 (in fixed output yoke
versions) is about 12-13" from the front of the case to the
center of the output yoke.
4. The shifter is a very simple lever operating a crossbar
between the two shift rails that plunge in and out of the front
of the case.
5. The ID tag is found above the front driveshaft output, and
will list model, manufacture date and gear ratio.
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