I wish I could find my pictures but I will try and explain: As you stated on end is flat and the other appears to be rounded. The flat end should have a hole and a nut that is captured in steel. that nut is for the body mount location which is pre-existing on the frame. Try bolting it up with the flat side to body mount and then the curved end pointing towards the wheel well and quarter panel on the outside side of the frame rail. I hope this helps I will continue searching for my pics.