1977 Body Bolt replacement

 I have been in the process of replacing (or trying to at least) all the body bolts/cushions...however, when I went to remove the old bolts in the rear, (behind the rear wheel) the bolt kept turning as it seems the nut (up behind the body support reinforced location) became loose (unwelded) or has stripped out.  As you know there is no access location as there is on the second body bolt location (in front of the rear wheel).

Question is...can anyone give me some ideas on how I can remove the old bolts given the current situation?
Thanks in advance.   

Your talking about the #4 body mount? Inside the car way in the back corner behind the wheel well is the cage nut your looking for. What I did on mine was to get a wiz wheel and grind the head of the bolt off and then got a punch and drove the bolt up into the car. Then I used a new nut and bolt with 2 people and put it back together. ( Mine is a 72)

Hey ezrider, welcome to the forum. I had the same issue on my ''78 and used the grinder method on the bolt heads-same thing Rich G. is describing. I replaced all the body to frame cushions and hardware along with some rust repair. It helped a great deal to have the interior completely gutted beforehand. Good luck and keep us posted.

Thanks Rich G for the post...yes I am talking about the #4 body mount.  However, don''t have access to the cage nut, It''s located up behind the fender well, the bolt itself is accessable from the bottom (inside the fender well area)...but I can''t see how to get access on any side even from the fuel tank side.  Only thing I can see at this point is cutting an access hole into the fender well to put some vice grips on the cage nut side...any other thoughts?  77 myst be quite different from a 72 i guess.    

Unless the moved the rear wall forward, you should be able to access the cage nut inside right behind the wheel well.  It is under the carpet.

Okay and thanks for the post 78buckshot.  Two owners telling me the same method is making me think really hard here :-).   
 
Okay, let''s say I grind off the bolt heads...then i punch the remaining bolt shaft up into the well...what next?  If I punch the old shaft bolt through, what will I use as a nut for the new bolt?  Or I still have the same delimina of not being able to access the nut area to hold it in place.
 
And if I punch the old bolt shaft through into the fender well, won''t that be rattling once you start driving the car again? 
 
Hey guys, forgive all the questions but my gears are turning. 
 
Last question, what does having the interior gutted have to do with mounting position #4?
 
Thanks again and looking forward to here back real soon.

Found it 73shark...thanks for the location. 
 
Now I understand 78Buckshot''s comment about having the interior completely gutted beforehand.
 
Ill keep you all posted on this progress.

I was amazed at how rusted mine were considering that they were inside the car.  But it was a daily driver for me for about 20 years and saw a lot of salt.  The #4 reinforcement is pretty much toast too.  Got new ones to put on.  Not sure if I''m going to replace the nut cage tho.
 
Guess the water just wicks up thru the rubber mounts into the interior.