IF that fusible link was open, there would be no way the alternator could/should have worked for weeks - at this point I would have had that entire portion of the circuit apart and every connection inspected - I will admit that I don't have to deal with winter weather, but this is a task that should not take more than an hour or two.
Disconnect the battery, unbolt the underhood fuse panel, flip it over and inspect it - unbolt the connections to the main fuse, clean and reassemble, if you wish apply some dielectric grease for protection.