The power steering lost all fluid abruptly. The right (passenger side) piston on rack sprung a leak. The parts department of Cadillac says that the pump must be replaced with new rack for certain serial numbered cars. This leads me to believe that an engineering change was made and the new rack is not functionally compatible with original pump. No one at Cadillac can or will explain why. I think it is a safety problem and GM doesn't want the cost of a recall. I wonder if GM has gone to Toyota for advice on how to screw up.