I have a 2005 silverado ext cab. Chopped 19" off back seat welded n stitched seat up. Built box that is 31" tall x 19" wide x 20" deep. 3/4" mdf. Port is 4.5" wide n 18.5" tall. Port is on bottom following side n around back. So total port length is 4.5" x 18.5" x 32". I'm gonna try to get pics up on here real quick it said total volume after compensating wood was 5.527 cu ft. But for the life of me can't figure out what the port is taking up. And what my tuning is at either. Plz help... I'm workin on pictures.