Shimano 600 semi-platform pedals are early to late 80s, as is the Laprade(the prod, we called them). I think maybe you have a mix of "take offs" from a shop.----- Items that were part of the bike as sent to the shop but not assembled(or removed) because the purchaser or shop wanted to upgrade. For instance, there is nothing wrong with a Laprade post, but they're ridiculously heavy for an alloy seatpost. The pedals might have come off for a variety of reasons--casual riders can be uncomfortable with the "swing and stab" needed to get your feet into the caged pedal and may prefer a full platform. (in case you don't know, pedals like the 600 are designed to be used with a cleated shoe and are only so comfortable as a platform). Some would have removed them to go to the new LOOK style step-in pedals.