My 2000 F1505.4Scab4x4 right side rear axle seal started leaking at about 80k miles. The new seal cost about $6 as I remember. The bearings looked good as well as the axle. The diff fluid needed changing anyway because the TL clutches had started to chatter. The hardest part to me was I tried using the silicon gasket maker like the factory did on the diff cover and i didn't do it right and it leaked. I'd recommend buying a gasket to prevent this fiasco. The synthetic fluid mine required was expensive available only from the dealer at that time. And I had to use two bottles of modifier to get the clutches to quieten down.