From what I can recall, there are no weak points on the chassis and the 110 non military ones are almost the same between CSW, 3 doors, double cabs etc. If there were that many which failed we all would have been on the hunt for new or better ones.
Water can get into to some areas, but apart form that and rust resulting from justifiable reasons, I cant recall any common weak points. I found rust between the gearbox cross-member and the chassis, which again I can expect, but there are no common weak parts IMO of the chassis.
What you are referring to as rebuilding BTW? Is it not better to buy a chassis in good shape?