I had my transverse muffler on my '68 replaced last week. When I picked it up the muffler guy said " we gotta a problem" Yikes my heart sank!! My muffler bracket somehow got dislodged from the floor plan. I dont prentend to know the name of all parts and pieces of my entire car. I thought I would get that out of the way. However looking at the bracket, there are two bolts with (threaded grommets?) that go through the top of it into the floor pan. There isnt a nut on the top side of floor pan and no way of accessing it. I dont see a way how the grommet is secured other than the bolt expanding the grommet???