I had the same issue noted above,exact. I preferred CPPs style the best but the Driver's side hit the frame flange. It to took a month to receive. I called the tech line and was told to clearance my nice powder coated frame. What a waste of my time. I drove them 100 miles round trip to return to summit..
I was watching Overhaulin a few nights later and they had the same problem with a 55 chevy. CPP gave them great service and swapped out for a new set.. This is obviously a problem for a lot people. The shafts just have to be a half inch wider. The factory didn't punch the bolt holes in the exact same spot on these frames. It's too bad for CPP Im just in the beginning stages of my restro and was going to spend thousands of dollars, Brakes,rear control arms,lowers.