I have served 16 of my years overseas and have also used an FPO address and yes this year they asked for physical street address. Every building on your installation will have a building number and street name/housing area. You either have to contact your housing office or base facilities to get the exact information. It should also be on housing agreement, or lease, and I know it sounds weird because I live on a street that does not have a name only a housing area, but everything was accepted using that address. Hope that helps.
John
