I have also noticed differences between Unicomp keycaps and IBM/Lexmark keycaps. With IBM and Lexmark, the Alt keys and the System Request function were printed in green, and the functions on the numpad were printed in brown. However, I believe this was eliminated by the time Unicomp bought the clicky keyboard design. Maybe the letters/functions on the keycaps were also applied differently. Due to those variations, would you be able to tell some information on the keycap you chop up (like Unicomp vs IBM, etc.)?