OK here's the update:
I ordered two of these with the swivel option.
These people seemed on the ball and knew what would fit the Sprinter.
I told them specifically I didn't want to jerry rig, or cut, or drill holes.
They were willing to have me send my rails and they would attach them
to the seat - or they said the swival attachment would work as a bolt on.
Swivil is a good thing anyway as it would be great to eat lunch in the van and swival around and talk to
the people in back.
I ordered mine in gray so they said about 3 weeks to make them. Also if I wanted they are in LA and have a place that installs
them but said it no problem a few bolts in and out.
http://www.discountvantruck.com/rvhighbackcaptainsseats/motorhomefurnitureDeleon.htm