blazer top problem

[lapranch]

I recently pulled the top off my 79 jimmy for the first time however previous owner had it off many times since it was new.
my question is about the nuts in cab and rails that the bolts go into.
First, does anyone know how those are attached since they move around side to side.
My problem is one of these nuts has broken loose on top of cab and is rattling around. Is there an easy way to fix or replace these without chopping up the sheet metal.