I would very much appreciate knowing if the barrel of my Parker Duofold Rollerball is compatible with the section of a Parker Duofold Fountain Pen. I'd like to save some money, if I could, by using the barrel of my rollerball as the host for the section of a fountain pen. Also, is the telltale sign of the difference between the Centennial Duofold and the International Duofold the decal on the top of the cap? You know, a banner with the word Duofold inside the banner, or a circle with a "daisy" inside the circle and the words "Parker" and "Duofold" outside the daisy. Now that I think of it, maybe I should Google a few relevant words and maybe the internet will provide me with some answers. Until I do, however, I'd appreciate some answers from you Parker fans (fanatics?). Thank you in advance! Don, ccvinylman