The sidecar mounts shown were included with the parts of a basket case R4 (restored and long gone now). There was evidence that the R4 frame had at some time had sidecar mounting hardware attached to it so I have reason to believe that these are period correct. The mount on the right has been fabricated and is flat on the frame side. The mount in the middle is concave with flat ribs on the frame side. Ball diameter on all is ~1.175". I'd like to get these items connected to someone who has a use or interest in them. If anyone on here is interested in these items I'll box and ship to ConUS free of charge.