Just watch out what year it is, the 9 1/4s in the newer pickup trucks had a lot of problems with breaking, there was a NHTSA investigation into the 9 1/4's that came in RAMs they where failing at highway speeds.
"Limited slip differential...AKA (LSD). Very common issue with the factory Mopar 9.25" LSD is for the Clutch Pack reatiner clips (commonly reffered to as the "c-clips") to wiggle themselves out of the carrier and cause serious damage. In late 2005 Chrysler changed manufactures which beefed up the retainer clips and slowed down the problem; however, it still has been occurring but at a rate much lower than before. This pertans to ALL 9.25" LSD rear-ends that are in 1500's only. Some guys remove them, but over time the clutch packs will move around in the carrier and cause wear/rubbing on the inside. This will wear out the friction discs as well as the inside of the carrier. "
