Do you need the inner seal when using these?
Agree with Jack. The inner seals keep rear end oil from getting to the bearings and diluting the grease held in by those fancy outer seals. The inner seals are the more important ones. In fact, I suspect the expensive outer ones are superfluous if you have good inner seals. I expect in that case a $6 set of original type outer seals will do.
Steve's right. The inners need to be in good working order to prevent thinning out the greased outter bearing with diff lube. The neoprene inners are about the best out there. In fact the outters shown would prevent you from finding out the inners are NG by retaining the leaking diff lube.
Those new neoprene outers are better than Ford design. Use these and they last.
The old cup, felt, and washer design has faults, found many washers cut from the axle key, bent from the Hyatt bearing slipping sideways, as it does, and gouging of the axle shaft by that now deformed washer.
The new outers fit snug, the inner surface provides solid stop for the Hyatt roller end, and they end any grease leaks.
The outer neoprene seals are great but are not necessary if you use our neoprene inner seals. If The outer bearings are filled with grease ,not oil. If the inner seal keeps the oil out the original Ford outer felt seals will work just fine with no leaks.