I would go ahead and replacing everything. Why take a chance with a worn bearing or seal. You'll be way ahead of the game if you go ahead and upgrade to the 3:55 gears while your there.
Both Tim and myself followed a fellow truck owner by the name of "Sweet" by putting in all new stuff along the 3:55 gears. Tim and I are enjoying quiet sounding rear ends due to all new bearings and seals. The 3:55 gears are a nice addition and help the highway cruising speed also.
