[Oldsguy]

bones,
Look real hard for those lock tabs, I have seen them so rusted that it appears they are part of the bolt head. If, they aren't there, or after you remove them, you still can't get the bolts out you might try a vice-grip wrench, about the medium 6" size should work. You won't want to re-use the bolts anyway after you get them off so don't worry about damaging the heads. Your best bet would be to take them to a media-sand blasting outfit to clean them off if that is what you are after. The will rust again though so why worry, just use a good steel-wire wheel to clean them up enough for correct re-assembly. Then go back and re-tighten them next week, and the next.