You should demand the NFRC stickers. The windows should never go the homeowner without those stickers.
Other than that, you can check on one of the window stickers (usually inside the sash pocket or on top of the upper sash rail) and see if you can find a build sticker or a specific model number related to that window.
After that, go to http://www.nfrc.org
and go to the certified products directory and start there.http://cpd.nfrc.org/pubsearch/psMain.asp
I read your post on the other thread. Very sorry to hear of your experiences to date. Stay the course and don't settle until you are satisfied. Most companies, regardless of how treacherous, will make things right in the end.