Bought when they were on sale on Amazon. I set them up on a Comanche 89 during a single axle rebuild to a Dana 30. They install very smoothly and provide an excellent seal, preventing debris from entering the pipes. Since I rebuilt an axle on the passenger side, the seal on the diff is just a lip so they provide a secondary seal if a lip starts to fail. A note because they prevent diff fluid from splashing. In the event of seal failure, it is highly recommended that the differential fluid be checked at every oil change or after hard driving to ensure the internal seal in the differential is not failing. Edit: Drive less than two weeks (maybe 75 miles) and the outer seal broke on both sides. Grease spatters everywhere, thanks for the disc brake fenders or I'd be dead. I'll contact the manufacturer on Monday.