system/priv-app folder missing in 4.1.2?

been searching for system/priv-app folder but can only find system/app. i'm using file explorer on a rooted galaxy tab 7.7.

1. can i install trebuchet.apk to system/app folder?
2. or can i create new folder - system/priv-app and place the apk there.

been searching for the forum but can't find no related topics. can you lead me to the right directions? :confused: