Originally Posted by 66GMC
It looks like you could get a sawzall blade in between there.
The other option might be to buy a cheap 9/16" open-end wrench and then bend or cut it in such a way that you could sneak it in there, slip it on the head of the bolt, then jam it up against the frame rail?
If I saw it off then how am I gonna put it back together when there is still half a bolt inside the hole? Also how am I gonna use a 9/16 wrench when the bolt head is one of those that require the use of an allen key or hex socket. Also the inside that you tell me to reach is not a nut. It is an insert with threads to accept the bolt. A wrench will not work on any of this.
The bolt head looks like this pic.