Yep. It's not too hard as long as you have the raw material and the tools (especially a welder) available. But it's sometimes easier, less frustrating, and less expensive to buy something ready for install.
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OP - your alternator should be replaced if you want to save your batteries, FICM, and injectors.
Good reading: http://powerstrokenation.com/forums/attachment.php?attachmentid=34810&d=1360377195
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