After a number of consultations and the perusing of available Simplex catalogs online I have come up with a photo dateline and short description of the variations found on Simplex "Criterium" shift levers from the mid or late 1960's through 1980's. If any list members can add to what I have been able to find, please contact me. There is an earlier set that I have seen described as "Criterium" but I can find no information on them. The photos in the link are shifters that I own or have owned.
http://s517.photobucket.com/
Jay Dubiel
Halifax, VA USA