The alt. Disconnect the "batt stud" wire and the 2 field leads(everything) from the alt & with your VOM check ohms on the 2 field male terminals(I forget the specs on them), continuity between either of the above terminals(check both) to case(should be none) and continuity between the large "batt" terminal and case(should be none). to double check take another minute & take off the fan belt & spin it by hand(in it's direction of rotation)& recheck. EDIT take a close look at your field terminals/brushes as the dead short may be right there.