leaf spring hanger question

setting up to put an 8.75 and new rear leafs on the 68 barracuda

got the car up on lifts and soaking every fastener I can see with PB Blaster
question,, on the leaft spring hangers,,

On the front hanger bracket I can see the threads on the leading side,, fastener looks to be a pressed in stud,, important fact is I can get to both sides, if I need to drill the fastener out, I can do that.

The rear shackel bracket does not look as friendly,, I can see the hex side of the bolt,, but not the wrinkles,,
Is there a weld nut on the back side?
I am thinking of drilling an access hole in the trunk floor to at least get some penetrating oil on the threads,, If nothing else, If I end up drilling those bolts out, will need access to get a nut on,,

Or do these normally thread off OK,, or is there a better solution for the rear shackel bracket?

thanks