Upgrade your tractor's performance with our high-quality aftermarket Cummins 4BT Main Bearing & Connecting Rod Bearing Set STD. Designed for models 4B, 4BT, 4BTA, 4BTAA, and 3.9L, this set ensures durability and reliability. The package includes 1 set of Connecting Rod Bearings and 1 set of Main Bearings, interchangeable with OEM part numbers 3901170 and 3802070. Trust us, a leading supplier and distributor of tractor and skid steer parts, to bring you the best in aftermarket solutions. Enhance your machine's efficiency and lifespan with our superior bearing set.