Another difference is the type of chainplates (cadènes). It is known that up to the year 1972 they were of the stirrup (étrier) type. From 1973 on they were of a single M14 bolt type. On my boat (#320, 1975) the size of the bolt is M16, a size which is also found on the posterior Gladiateur.
It might be interesting to know around what serial number exactly the different types were changed.
Best regards,
Tom.