Yeah, that would do it. I just wonder what else they missed if they never tightened those bolts. Hope everything else is okay.
As for torquing, I don't think you will strip the cradle bolts. You would need a long bar to do that. As it is, I put a long bar on the end of a 28" breaker bar to tighten mine and I don't strip them. As for figuring out how much 100 ft/lbs is. Your lugnuts are tightened to 100 ft/lbs. So next time, try to loosen one of those and see how much it takes to loosen it. Then tighten the cradle bolts to at least that...plus some more. I don't usually worry about torque specs on stuff like that. Just tight.
