OKAY... so.. I think I understand it now.
rippers were 1/4, and they were (most likely) literally modified versions of the eu17 blades which had the clip point already in the design.
st rippers were 3/16", and were modified versions of the zero tolerence ergo handled natural outlaws. these had the characteristic ergo drop point, as well as the characterisitc zero tolerence deep swedge at the tip. the handle was modified into the eu17 style handle.
pics of the st-ripper.
http://www.bladeforums.com/forums/showthread.php?t=404770&highlight=ripper