Looking for old Custom Box Thread

[Empurfektion]

Sorry admins but I've been lookin for some time now and can't find that "Do it yourself" custom sub box that fits right behind your back seat. Can anyone help me find this? I just got a Kicker 12 Sub and Amp and there is literally NO room back there. Wanted to see if I could find that post to take to the local shop and see if they can help me install that bad boy.

Thanks!