Here's another link to the date deciphering info:

http://www.flickr.com/groups/olympustrip35/discuss/72157594537718351/

People seem to be missing it so here is the key info:
The code consists of 3 characters:
1st Japanese character or letter (in later models) signifying the assembly plant.
2nd number representing the last digit of the year of assembly
(e.g. 5 = 1975, 0 = 1980).
3rd number or letter representing the month of assembly,
1-9 for Jan-Sep, X, Y, Z for Oct-Dec.
for example; N1Y = November 1971

Of course the TRIP 35 was manufactured between 1967 and 1984, so if you are unsure if you have a 1968 or 1978 model, the chrome shutter button is the earlier and the black the later.