Winston, thanks for looking this up for me! I'm not sure what you mean by double nuts underneath. Here is a pic I just made of one side:
You can see that the lock washer is not yet tight and the end of the bolt is almost touching the radiator already. I took the radiator off on my carport, so I'm sure there was nothing else on there. If I tighten it down much more, that bolt is gonna be up against the radiator at the least, and maybe go thru it.
I didn't realize how close it already was until I just took the picture. I'm thinking maybe put a stack of washers on the underside of the bolt to essentially make it shorter, and then put a nylon lock nut on the top to keep it from working loose. Is something like that what you were talking about? I don't understand how this didn't already cause a problem from the factory; I suspect I'm misunderstanding something.