I picked up a FD that was sitting outside with no cover and hasn't moved for 4 years. It had bent control arms and it was just left to die so I decided to grab it and revive it. So long story short, "everything" is fixed except that once she starts and gets to an idle, the alternator seizes up and the belt does a burnout. Not really sure where to go from there. Do I get a new alternator or is there something else I can do? Alternator rotates fine during ignition but once it's running it completely stops. Any advice would be great.

 

The bearings in the alternator have failed. Probably easiest to just get a rebuilt unit from a parts store.

 

Buy a "new" one. I found one for $50 for my 13B. Works great.
I have one for a 12A if you're interested.

 

I think there was a reason that the alternator was left outside for FOUR years!..It's Toast..can you spell Toast?..C-r-a..(ah,,just fuggin with ya..!).
Seriously,I have been picking up FD alternators for less than 100 shipped..so you can too..
If not,bring that old piece of Toast in and use it as a core!