I've googled not only this site, but more widely. The consensus seems to be that the K mount and the B mount are "very similar" as someone put it about a year ago, but I can't find anything more definitive. I got a Pentax K T-mount out of my little box and it does fit on a Praktica B mount camera and even the pin locks in, though the mount seems a little loose. Some makers of Pentax K to EOS adapters, seem to to hint, but not very explicitly, that the adapter will also allow use of Praktica B lenses on the the EOS. Just looking at the actual bayonet flanges on the Praktica B, the size of some of these seems to differ even among Praktica mounts (such as a M42>B adapter compared to a B lens mount). Obviously the B mount has the electric lens connections pioneered by Praktica in the EE series, but can K lenses be used manually on Praktica B models? Or can Praktica B lenses be used on K bodies?