Missing rubber bushings in springs?

If you look closely at the nuts on the U bolts they are specials. It's called a scored nut. To tiny dimples in opposing sides shop where it was put in a press and distored to slightly oval shaped.
So when they go on with speed they heat up and expand a tad. Once tight and cooled they contract again meaning no lock washer required and no chance it will loosen.
If you use a good penetrate to cut through the crud on the threads and a strong high speed impact that will generate some heat in the nut, it will come off. If you simply start twisting with a socket and breaker bar you will twist the leg of the U bolt which degrades the integrity of the steel. Either way though, those U bolts aren't supposed to be reused. I know, Lots of people do reuse them. I wont go to all this effort to save the 40 bucks. I cut the old U bolts with a torch or die grinder. Then me or no one else is gonna reuse them.