I'm trying to replace a fan in my bathroom.The old one is a NuTone 668RP. I've managed to get all of the innards out of the old fan but can't figure out how the housing is attached. I don't see any screws or anything and it seems to be attached from the top. It's a downstairs bathroom so I can't get to the attic.
There's a stud on the "bottom" side (in the photo) but the side is not attached to the stud. I stuck my screwdriver up there and ran it along all four sides. Must be attached to the top somehow.