U-Bolts: To re-use or not?

I say yes. That is IF the nuts come off easily. Usually, they do not. If they are very difficult to remove, it stresses the metal and I will not reuse them at that point.

Of course, if they are as old as you say, I would chunk them anyway. New ones are inexpensive.

Are you really that cheap that you want to risk the damage that can incur if they break?