NP271/NP273 Transfer Case Bearing and Seal Kit ZTBK485A

This is the full bearing, gasket and seal set for the New Process NP271 and NP273 transfer case used behind the manual and automatic boxes in 2003-and-newer Dodge Ram 2500 and 3500 trucks. USA Standard Gear part number ZTBK485A. It covers the slip-yoke rear output version of the case, so check your rear output before ordering: if the driveshaft slides into the case on a splined yoke, this is your kit. Fixed-yoke cases take a different seal.

Inside the kit are the case bearings, the input and output shaft seals, the front output seal, the shift shaft seal and the case-half gasket material needed to put the unit back together dry. Rebuilding one of these usually starts the same way: the truck marks its spot with red-brown gear oil under the transfer case, the front output seal or the rear slip-yoke seal has gone hard, and once you have it on the bench and split, the bearings that have been running in contaminated fluid are not worth reusing.

Bench order is split the case halves, pull the chain and sprockets, press the old bearings off the input and mainshaft, drive the new races in square, then set the new seals flush with a proper seal driver rather than a socket and hammer. Torque the case halves in a criss-cross pattern and let the RTV skin before you fill. Fill capacity and fluid spec stay whatever the factory manual calls for on your year truck - most of these run ATF, not gear oil, which is a common and expensive mistake on a fresh rebuild.