It was an F arm, not sure what year. It had phenolic bushings - they fell out when I baked the paint - so I got these from Germany and pressed them in. Using it now in the K3F hybrid I just finished.
Mine is a K5 arm, with no tophats on the original bushings.
There might be a clue in there (as to why some of these installations work, other do not): both of those arms have the same ID bore size, which is the larger size found on the post-1974 arms. This may be what the seller has in his bike, where he "designed" these from?
However...the collars were different between the K4/5/6 and the F2/3/K7/8 arms. The earlier collars are typically (new) 0.8438" to 0.8440" OD, while the later ones are (were) 0.8443 to 0.84445" OD on the outer half of the bearing area, and -0.0002" to -0.0004" from the outer on the inner half of the bearing.
Another question, if you remember it: was there a small relief cut into the 90 degree angle at the base of the flange? (To be exact, in bronze this should be a spherical relief cut.) At the size of these bushings, this would be about .010" diameter.
