Take it to an alternator rebuilding shop and ask if it is even possible to rebuild one and the cost. They may even sell you just the bearings if they are available. The other option is to take the bearing out and bring it to a bearing store. Assuming it is a 40 AMP alternator the bearings are M805135 and M805133. They are a bit pricey so you may want to see if a bearing shop can find a repacement bearing for those part numbers. If you do not have a 40 Amp alternator you can look up what you need at www.jdparts.com. Roger