Bolts do not fit the holes like a swelled up rivet shank. To use bolts, you should drill the hole to the next bigger bolt so the shank of the bolt fits tight to the holes. If the bolt is short with threads all the way to the head, it will not fit right either. To eliminate the twisting movement of the frame and attaching part, the holes must be filled 100% to simulate a solid mass, thats one of the reasons rivets work so well, zero wiggle room once in place.
What the movie, Master Hands by Jim Dandy films (google it), they show a 1936 Chevrolet being factory built. The rivets are put in cold on the assembly line with some very stout riveters.
Joe
