Where are Vaults 77 & 76 on fallout 3? (xbox-360)?

I found the vault 77 jumpsuit in paradise falls, and got curious about it. I searched a while, took the explorer perk, and was a quite disappointed :(. But then i remembered that one vault was in a garage, so i looked around a bit. I also remembered seeing a vault 76 on the vaut-tec computer in the citadel. Someone help, it's driving me nuts :)