Hi Vitor,
the first clue to the building year is that Parker quit the business sometime in the early 1990s, so your boat is at least 25 years old. I assume you didn't get a measurement certificate with it?
The IYRU number
is the "serial" number, and means that yours is the 28360th registered 470 in the world. As these are not
sail numbers and therefore not easily visible "general knowledge", it's a little hard to translate those into a building year.
The international class association might (well,
should) have the information. If not, all one can do is to compare that number with the numbers of other 470s with a known building year.
Is 1900 the
builder's number? Then it would be the 1900th 470 that Parker built, but that won't help a whole lot.
Nothing on the sails? If it's the sail number that you want to find out, then you have to contact
your national sailing authority, who manages those for nationally-numbered classes such as the 470.
You could nevertheless post a few pictures of the boat which could help determine the approximate vintage. Structural and equipment details would help, as well as shots of the IYRU and builder's plaques.
_