It would appear that the original question wasn't answered here...I'm in the middle of diagnosing a similar problem and discovered the location of the fusible link in my 2003 7.3 SD. It is at the end of the black and orange wire which runs from the back of the alternator to the battery. Mine has the FL at the battery end and it's covered by a piece of black shrink tube making it look like part of the wiring insulation. It would appear as if the wire and link are replaced as one piece, they are fused together, shrunk wrapped at the ends, then shrunk wrapped again over the link. It's a grey double wire 12 ga. link. my sincere thanks to all who have posted about this. It made my search much easier.

 

ON A 1997 F150, WHER IS TH FUSIBLE LINK LOCATED???

 

 

Here’s a diagram of fusible links...