Note all the caulk around the woofer. Odds are that these were 15" 604Es that were surface mounted. But the strenghtening ribs get in the way of a flush mount leaving a gap to be filled. Later versions (mine) use a 16" 604E2 woofer that allows for front mounting because it puts a smooth mounting pad beyond the ribs. The first Super Big Reds in my home (lasted for two cuts before they went back) were like this, but without the caulk and you could see the ribs cutting into in the baffleboard.
