I bought them (Dawson Plugs) from Henry Yeska, Sr., 825 Georgetown Road, Nazareth, PA 18064, 610-759-0230 - and they were 100 point ready to install.
P.S. Learned the hard way, run a pair of dial calipers down the hole prior to installation and make sure you have the right depth prior to installing. If depth is wrong, very carefully clean/drill out hole (which is not easy) as they holes are sort of oval.