need a nut size if someone can help (1 Viewer)

[wakesetter]

I got a new Bosal muffler last month and put it on, but somewhere along the process I either lost the nuts for the muffler hanger mounts, or I put them on finger tight and the shook off. I'm getting a super annoying rattle from the front hanger right now, but don't know what size bolt to grab at the hardware store. Just to clarify, the hangers are Toyota original, as were the nuts that I lost, not looking for a Bosal part.

Thanks!