I took a closer look at the thing while I was trying to re-install the back seat (need two more bolts), and it looks like the PO took the stock rails out, and installed the power mechanism in their place. The adjustability is great, but the power mechanism is about 3 inches tall, which makes the car hard to get into, I smack my head on the door when I try to check the drivers side blind spot, etc. I can deal with manually adjusted seating.
On a side note, what is directly underneath the rear seats, if you were to, say, drill a hole through the floor to mount a rear bucket seat?