Over time all internal engine wear surfaces become worn. This is true for crankshaft journals, connecting rods, camshaft lobes, piston rings, bearings, etc. When rebuilding a worn out engine you'll need to replace them all in order to regain the engines original performance. And, lets face it, Jeeps need all the power we can get. OMIX offers new high quality replacement engine parts to get your Jeep back on the road. This replacement main bearing set fits 72 - 83 CJ5, 72 - 75 CJ6, 76 - 86 CJ7, 81 - 86 CJ8 Scrambler, 72 - 73 Commando, 72 - 73 Trucks, 72 - 83 Cherokee Wagoneer, 73 - 74 DJ5, 84 - 86 Grand Wagoneer, 87 - 90 Comanche MJ and 87 - 90 Wrangler YJ models equipped with 3.8, 4.0 and 4.2 liter engines bored 0.020 - in. over. Replaces OE 4289M.020