Oops, I goofed... the truck has a 207 which was used prior to the introduction of the NP 231. The NP 207 is designed for smaller-displacement engines (input torque rating: 610 lb.-ft.) in vehicles with GVWRs of less than 5,000 pounds.
Credit to http://www.offroaders.com/info/tech-...rans/trans.htm For the above info.