I don't know about a 42 but my 37 took a carrage bolt, 2 per side. Yes, it does go through the rad. support brace. I had to snake them through the radiator frame with mig welding wire.Just wrap it around the bolt after feeding it through the fender side. Then gently pull it back to fit it into the square bolt hole. It takes a little practice but can be done. After you get the first one through place a nut on it to hold it in place. I used SS carrage bolts from Home Depot. Can't give you a pix as it is in place.

Al