If you need bearing seals, you should repack the bearings. Furthermore, if the seals leak, your brakes have probably been ruined. Brake shoes soak up the grease. A new loaded brake plate for 12" drums is around $75 each. Seals can be purchased at NAPA or any reputable auto parts store. I don't have the part numbers handy, or I would relay them to you. Do a search on this website.
2003 GMC 2500HD 4X4 D/A Ext. Cab
Propane Powered Honda EU2000i
Lots of Hot Sauce!
Air # 283