Frustration is always part of the game.
quote:Putting pressure on the underside of the bracket as I tried to back off and remove those nuts didn't work either
Well, that is exactly what I would have done. And if it didn't work the first time, I'd keep trying. I can see no other, or better, method of getting those nuts to thread back off.
My 72 is 2511. On my chassis those threaded studs are tack-welded to the chassis, somewhere along the piece by piece assembly of the chassis. They are not bolts in the sense of having a hex head, but a round-headed stud. And they can not be accessed once all the pieces are welded up.
I had the misfortune of having one of those studs snap off at its base.
My solution was to drill, starting small and working up in diameter, (so as to not bind and snap the tack welds) the tack welded head of the stud. When I reached the proper diameter for the 8MM (I think they re 8mm) I tapped threads and threaded in a replacement stud.
I was able, not easily, to get an 8mm nut dropped down the small channel (again, your chassis may vary) behind the studs, and hold it in place while I threaded the new stud into it.
Really though, just a stud threaded into the drilled/tapped stud head should suffice, as once you tighten down the brackets, there really isn't any rotational force to unthread the stud. It will be in tension and should just sit there doing its job.
But yup, those damn nuts have to come off as the first step.
Larry