Glass and Mirrors - Mirror hanging hardware?

I need to hang a 3' X 6' mirror that is attached to a 1/4" hard fiberboard with docorative clamps around the edges. The fiberboard has hanging mounts attached (and I would like to use those mounts), but my problem is that I don't have the pieces that go into those mounts.

The two pieces that I am missing need to have a 3/4" wide circular head about 1/8" thick with a 1/4" round shank coming out of that circular head. To better describe this missing piece, it would be like a nail that is 3/4" across and having a 1/4" diameter shank. The shank would be about 3/4" long and would have a hole in it, through which I could put a hanging cable that would go over bolts that are screwed into studs on the wall.

Is there any source available for this missing hanging piece that I am describing? If not, then I will have to start from scratch with another method of attaching fasteners to the back of the mirror/fiberboard.

I have looked on the Internet mirror hanging hardware but can't find anything like the hardware that is already attached to the fiberboard. Any sugestions?

I found the right hardware. At Lowes they have a big section of miscellaneous hard-to-find hardware. I found a T-Nut that fits into the devices that are attached to the back of the mirror. I bought two small bolts (that screw into the T-Nut) and I bought two small straight brackets.

So a bolt goes through a bracket and screws into the T-Nut, which slides into the fitting that is already on the back of the mirror. Then the other end of the bracket will attach to a large wood screw which goes into a stud on the wall. Problem solved.