Generally Ektachrome do date their slides but Kodachrome ones are hit and miss.
These are paper mounts and say eg 'Jan 8 M7' probably mid 1980's - Defenitely nothing after the 8 - maybe the printer had a bad day

Others are clear 'Feb82 M6' which makes me wonder about the missing digit.
Kodak had a brief period with white plastic mounts and not a mark in sight which was helpful. Other times on plastic mounts it just had month stamped - no year.
Does the M7, M6? etc indicate naything useful?
Not sure where to post this so gave this area whirl.