Description Kit Masters’ patented Auto Lock feature will AUTOMATICALLY LOCK UP fan clutches when the friction material nears the end of its life, allowing the vehicle to finish its trip. Repair or replace the fan clutch in your shop, at your convenience. No outside labor costs or tow bills. Application Peterbilt Caterpillar 3406E Peterbilt Caterpillar 3406 Peterbilt Caterpillar C15 Peterbilt Caterpillar C16   *There is a $250 core charge. Cores can be returned for a $250 refund. Fill out and print the form below and add it to the return box, send cores to: SP Truck Parts Core Return 30026 Beverly Rd Romulus MI 48174   Fan Clutch Core Return Form