If I understand the description correctly, Scott Davis has these for sale at
http://www.sdbicyclegarage.com/
Regarding Robert Brooks CR query "... a mid 60's PX10 .. the rear-drop out adjuster broke ... try to find a replacement.... help me in locating one or a pair of these adjusters. These are the ones that look like spacers that fit inside the actual drop-out..."
Peter Brueggeman
pbrueggeman(AT)ucsd.edu
San Diego Calif USA