Centrifugal force can throw the rear end lube out of the housing and into the right side wide 5 hub.
This can cause wheel imbalance and the ring and pinion to run dry, and also makes a mess to clean up.
Seals-it Wide 5 Hub Seal:
Keeps the rear end lube out of the hub and grease in the bearings.
Light weight aluminum with bonded neoprene seals.
Installs by hand, no need to remove bearing races.
Works on front hub