What you are looking for is called a Speedi-sleeve manufactured by SKF Braeing company. It is a thin (.010?) thick metal round tube the slips over the length of the seal bearing suface. it is secured with Locktite. One installed it provides a fresh surface for the seal lip to ride on. Very common on engines with high mileage.
http://www.vsm.skf.com/en-US/HeavyDu...eb_secure.ashx
GO to a good auto pars store, such as NAPA.