Look for a separate 4 digit code on the rating plate. That gives you the week and year of production. Since they changed their system back around 2004, they should be able to give you the correct valve rather easily. Just tell them the model including if standing pilot, DSI or IPI ignition and fuel type. If it is DSI, you would probably have to get a different control module as the originals are no longer available. Some were 24 vac and a few were line voltage. If you have further problems, contact FireSide Hearth and Home in Annapolis Junction and they should be able to help.