Behind the upright part of the backseat on my 72 is this thing... it's sitting vertical, comes up from the floor, goes up like a foot. It's maybe 8 inches wide... and an 1 or 2 thick... that's from memory cause I saw it a while ago and just got around to asking... I think the underside of the car may have lines or sorts going to it (maybe fuel) but I'm not all that sure... it was a while ago... Anyone know what the heck it is???