Ive seen this time and time again on blazers,I agree on grinding and welding,not sure the small hole is of any consequence. Be carefull when grinding not to make the metal too thin, the crack is from the stress of twisting and will def. have to be welded. anything else will crack.Backing it up with some metal is a good idea,just remember to treat the backside with some rustproofing when done.Try setting the welder on a piece of scrap the same thickness as always penetration is everything.