Yeah, I noticed that IBM's model numbers seem to change at random. And Lexmmark made four models of ANSI-layout Model M (cant remember exactly how they go, but they start with 4, 5, 8 and 9) that seem to be identical, and seem to randomly alternate between single and double piece key caps, and some have detachable cables, and others dont. Oh, and they were all made at the same time... It's a complete mess.