I have an 87 5000SQ NF. The alternator keeps throwing belts, and I think the reason is that the wrong bolt is holding the frame for the alternator. The bolt I am referring to is right near the crankshaft pulley and as far as I recall is the highest bolt in the frame. The one in there now has a 13mm head, probably an M6, but I can pull it out with my fingers by wiggling it slightly- no unscrewing necessary. Any ideas on the size?