shaq's is legit. D-Howard has a max of 375lbs and yao ming has a max of 350lbs. Shaq is bigger than Ming and has been around longer than howard. Ming is by far the most unbelieveable i know, but it's been confirmed by players and trainers. Him and D-Howard have a 'competition' seeing that both are the heir apparant to next best centre, neither one wants to be out lifted or out worked by the other.
I think all are legit, except wilts. I don't think the weight training in hsi time was serious enough for them to even care about doing bench press often enough, to build major strength. Make no mistake though wilt was an athlete of out of this world proportions. It's confirmed by Lew Alcindor (kareem) that he could jump and touch the very top of the back board in his early playing days.