We recently purchased an ex-van pool van and are in the midst of converting it. Originally it came with ten bucket seats with integrated seat belts. We have removed the ones we don't need and are looking to move the rest out of our garage as they take up a fair amount of space.
The seats come in two sizes - standard with a width of ~19" and narrow with a width of 17". Along with the seats are substantial steel bases with legs spaced to fit the "valleys" of the van floor. In the positions that did not utilize the stock underfloor braces, there are steel backing plates. They are all ~46" tall from the bottom of the base to the top of the seat, and about 24" from front to bask. All with integrated three point belts and pocket on back of seat back.
We have seven seats total - three narrow, with one single base and one double base, and four standard, with one double base and two single bases. All are heavy, so local pickup needed. I'm located about 45 minutes west of Baltimore, MD. I'm asking $75 per seat (with base).
Let me know if you have any questions are need any particular measurement.