34 tudor body to frame question

[Ken Arms]

Its been too long, I can't remember! Are these three holes for bolts to go through to help support the body? If so, carriage style round head? one hole out of the three is smaller. I put a partial new sub rail on the other side and I will need to drill these out, I just need to remember what they do. Almost seems like over kill. Old minds need to remember! I took pictures but I spilled coffee on the laptop so poof. Thanks Ken