Hey Ed,
I'm by no means an expert or anything on Suburban seats--your seat set-up sounds interesting. I'd love to see a pic of it! I haven't seen a ton of Suburbans and their seats, but of all those I have, I haven't seen the tracks you're talking about.
All the Suburbans middle seats I've seen are just an abbreviated bench seat--they are one piece, and don't run the full width of the interior. They run from the driver's side wall over about 60 percent and then stop, allowing people to pass through to the rear seat. It's a 2-person bench, while the full-width 3rd seat is a 3 person seat.
-Brad
