1) Yes, and can be sold as reconditioned units. But beware, be very aware, it usually lasts a couple of months for some.

2) There are many automotive electrical shops, one is Tower of David. They do accept alternator repair but it will take days before finishing it. No first hand experience with Sprint yet.

3) Not advisable to buy reconditioned/surplus units. Infact I use a locally assembled alternator for my rig which only cost me around 3K compared to an original unit pegged at 12K. What Tower of David does is collect the housing, rewire all the existing components with new ones, and bearings inside. I could attest to this, we currently supply them the bearings used. Quality assured those bearings will never get stuck. :D