Unlike a rear axle that is constantly lubricated by axle fluid, a front hub relys on manually packed grease to keep it lubricated. According to the service manual, the front hubs should be repacked every 22,500 miles. Every time the front hub is repacked, the seal must be removed from the hub to access the bearings. This means that a new seal is required every time you pack your hub with fresh grease.
This seal will fit 3800LB, 3880LB and 4000LB front hubs (2WD 250 and 350 trucks).
