Look in the kitchen cabinet over the sink. I also have a FEMA trailer and mine has the id label there. Mine has the date manufactured, what plant, tire sizes... and the product code on the far right top of the label. Though you may have three sets of codes there and the bottom of the three was the one I could translate into my model.
Depending on where yours was stored you may have a bit of work to do. Mine was never lived in (lots of stuff still in plastic). But exterior things need some work. For example the battery tray is almost rusted out, the hubs needed to be repacked, the tires that faced the sun are sun rotted, the LP quick connectors needed to be retrofitted, and my left turn wire in the junction box was not connected.
Good luck. I am having a great time working on mine and if you got as good a deal on yours as I did mine you can sell it for more than you paid for it!