NP231 Transfer Case Rear Housing Extension for Jeep

The rear extension housing for the New Process NP231 transfer case, replacing Jeep part number 83503156. It bolts to the back of the rear case half and carries the output bushing and seal that support the slip yoke. This version fits 1987-1995 Wrangler YJ, 1987-1996 Cherokee XJ and 1993-1995 Grand Cherokee ZJ with the NP231.

You replace this housing when the old one is cracked from a driveshaft that let go, when a dragged or bent yoke has gouged the bore, or when the bushing has worn oval and the rear seal will not stop leaking no matter how many seals you put in it. A worn bushing lets the yoke wobble, which shows up as a rear driveline vibration and a wet transfer case tail.

On the bench: drain the case, pull the rear driveshaft, unbolt the old extension and clean the case-half mating surface down to bare metal. Seal the new housing with RTV, torque the bolts evenly, then install a new rear output seal (Omix 18676.29, sold separately) and check the yoke for wear before it goes back in. A grooved yoke will eat a new seal in weeks.

Cast alloy housing with the output bushing already pressed in. It does not include the rear seal or mounting bolts. Not for slip yoke eliminator (SYE) conversions, which use their own short tailhousing.