Well you have a couple choices, but generally they put one at the bottom of the body…where a trapeze tailpiece or a Bigsby would attach, and the other one in the center of the heel of the neck (right where it joins the body). : I recently bought an Sg body and neck off ebay, and it only came with one strap button, if anyone has an idea as to where the other strap knob would go, and I also need help finding a back plate.