I used bolts with a 1/2" Diameter shoulder, 3/8" diameter thread, and reamed the holes to size with a 1/2" hand ream after drilling the holes to the size just under 1/2". If you're interested in re-riveting, Deve's Technet has a whole picture show with him re-riveting a crossmember.

Last edited by Norcal Dave; 05/29/2017 7:16 PM.
~ Dave
1950 Chevrolet 3600 3/4-ton with 261 engine & T5 Transmission