I'm getting in my way-back machine for this so don't crucify me if I have it wrong... I don't think the PDP #'s relate in sequence. They are just an order number and may be common to any Yamaha product. More important would be the serial number. More specifically the last 4 - 5 digits. These are sequential numbers for the market in which the bike is sold. So, look for all the North America bikes to be in the same run of numbers (I think this will include Canadian bikes, too.)
So, watch Micapeaks's list and see who has the highest registration. Keep in mind that only a minor number of owners will post there so you'll have to do some estimating on the actual number of bikes ordered. 2,500 seems way low, IMO.
It has been reported that the '03's came in around 2,500; '04's at 3,500 and a similar amount for '05 which I highly doubt. The last time I checked the list for '05's first run of PDP bikes, the highest number I saw was 3,680 or so. That was just the people who cared to post, so there could be more that are higher. Then there was the 2nd PDP which only added to the total. I'm guessing the '05 run was 5 - 5,500 bikes. Again, just a guess.