Just as important, shock waves travel though the car when it hits bumps. If the radiator were hard-bolted in the core, it would become a solid mass with a core, just like a brace provides more rigidity to an open part. As a result, the shock waves would be just like constantly beating each solder joint with a hammer every time the car hits a bump. If the radiator is hard-mounted only on one side, it allows the radiator to float independent from shock waves. As for which side they selected to hard-bolt, the slush-box lines makes [censored] good sense.