[redmodelt]

Don't know how easy to put nut back on the bolt at this point. The leafs may have shifted so as the leafs are being compressed the bolt may just work up so past the top of the frame with no way to keep from turning when a nut is installed.

Another option; Could make up new longer U bolts to act as a cage. Jack up the car and put frame on stands, leaving the jack under the rear end. Replace the U bolts with the longer ones, leaving the shackles on for now and room for the leafs to drop down thru the U bolts. Lower the rear end to take tension off the leaves. Once tension is off the leafs, remove the U bolts and leafs and use the spring spreader to take main leaf off. The other option would be cut a hole in the hump covering the center, drive the old bolt out from the bottom using a tapered punch so holes will line up as it is driven out and install a new bolt.