Farmall Cub

I don't know how to mount this muffler. Four bolts are supposed to go through steel brackets and directly into holes in the muffler. The hole in the brackets and muffler don't seem to be threaded and the bolts don't screw in. It seems like I need to use a lot of force to screw in these bolts. Does that sound right?

Something sounds off. Did you take off an old one? Could you post a couple pictures of what you're working on? I tried to look up a pic of that part number but no pic.