Rodenstock APO-Rodagon 300mm f/5.6 lens cell set. No barrel, but good as a project. M67x0.75 male mounting threads on the cells. Per my measurements, the distance between cell mounting flanges is 55mm, while the air separation (the gap between rearmost ends where the diaphragm/shutter blades would normally fit) is about 22mm. The rear glass diameter on each cell is 40mm.
The lens glass has no scratches or fungus, but there is translucent rainbow-like separation around the edges and very faint hazy spots or cleaning lines. Overall, I think it is still pretty useable.