The company that powder coated the control arms for me took uppers and lowers cross shafts out. I neglected to take a picture of the lower control arms before I took them and they came back to me unassembled. One of the cross shafts is flat while the other is round and I didn't know if it made a difference which side the flat cross shaft went on. My 1961 Impala bubbletop has a 348 big block in it, I don't know if that makes a difference. My wife's 1961 Impala flat top has a 283 small block and both cross shafts on the lower control arms are round