Sound like an over charging alt. could be causing the problem.
Dash meter, in my 92 loyal run about 13 volts, and with meter at the battery about 14 volts, if its pushing 16 volts that is a problem.
Not sure about subaru reg. but most dump to ground, so a by ground o reg. can cause problem.
The other choice would be a place in the wire that is worn and when going down the road, short out, I do a shake test, shake the hell out it.
And as for fuseable link, just use a wire 2 gauges smaller then the factory wire, and will blow first.:banana: