This is a great resource and should provide you with some more information. http://www.hasselbladhistorical.eu/HS/HSTable.aspx

For the record when the 500CM was introduced the 500C badge was not updated straight away. So if the camera says 500C but has a interchangeable screen it is actually a 500CM.

VHPICTURES
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Use this table to get the year of manufacture from the serial number.