Vehicles made by American Motors Corporation (AMC) and Jeep incorporated a variety of transmissions and transfer case systems.
All transfer cases were available with inputs matching either 21- or 23-spline shafts, making transmission swaps possible among various models and years.
However, the depth of transfer case input and length of trans output (measured from the mounting flange) changed, and there is 15/16" difference between early and late models.
Some sources state that the output shaft spline change occurred for the 1990 model year.
The input on the transfer case can also be changed to match the output shaft spline count.
Other than the bell housing pattern (main transmission case) and the torque converter, the AMC version is the same as other Chrysler transmissions—all parts interchange (torque converters do not interchange - unlike the Chrysler torque converters which have a pressed on ring gear for the starter teeth AMC uses a traditional 164 tooth flexplate similar in design to those used by Ford.
Jeep has used three different transfer cases made by the Spicer Division of Dana Holding Corporation.
Most other transfer cases used in Jeeps have a centered rear output that lines up with the input shaft.
The Dana 18 always has gears turning, which makes it noisier then some other transfer cases when in two-wheel-drive mode.
Applications: The Dana 20 can be identified by the center rear output, cast iron construction, and deep oil pan.
One exception is the version used with the THM400 in full-size Jeep trucks, which used a different spline number on the input gear.
Applications: The Dana 21 part-time gear system with single-speed case with automatic transmission.
The 1980 factory original came with a shorter tail housing and a longer rear drive shaft.
The second digit is a series number that reflects design, and provides minimal information about torque handling.
Interchange ('flip') is possible, but there is an indexing lug in the pattern, in an attempt to allow the transfer case to attach in only one position.
The later version (1996 and beyond) had a viscous front drive, creating a rear torque bias, but included a provision to lock the center differential.
A complete T96 with overdrive is 18+3⁄4 inches (480 mm) long from front of case to end of tailshaft housing.
A unique feature of the Dana 18 is the overdrive that attaches in the PTO port in the back of the system.
Laycock de Normanville overdrive was available from 1974 through 1976 for inline six engines with the 150T and for V8 torque tube cars with the T89.
The bell housing bolt pattern for the old AMC 196 Straight-6 engine is the same as for the more modern early 199 and 232 (used from 1964 to 1971), but the 196 had different dowel pin sizes.
The bell housing for six-cylinder engines changed to match the V8 in 1972 when AMC switched from Borg-Warner to Chrysler transmissions automatic.
The Iron Duke I4 used by AMC in Jeeps from 1980 to 1983 used the standard small block Chevrolet bolt pattern bell housing.