What kind of harsh vibration are you experiencing? The fire and police department that my work supports use Toughbooks that seem to use regular laptop HDDs. They are seriously banged about and the HDD was the least of their worries. It's the batteries that's gets worn most.
I'm not sure if the design of the Toughbooks, perhaps the drive bay is dampened or just that laptop drives (which are being used most for external portable storage) are being designed for a harsh enviornment in mind or both. But if I were making the decision then the 64GB SSDs would be it.