I ended up with 6 of the Sienna seats. Which is why I'm selling 2 seats. I used a fixed mount for the second row from UJoint and the MG Metal Works mount for the front. I can remove the seats in the second row in about 5 minutes each.
The passenger seat is a swivel mount. Driver side just slides forward and back. I think he might have another set of front mounts. They are not cheap seat mounts, but they are really well thought out and built.
The front mounts are designed to work with the Sienna recliner style seats (though one guy was able to fit them to the plain ol' cloth bucket seats without much trouble). They are the second row seats from the Toyota adapted to work in the front of the E-series.
I disable the recliner foot rest on the driver side (since it isn't usable) and the passenger side will swivel around for full use of the foot rest. These seats are a nice upgrade over the stock seats.
Sienna seat long gone. Found out shipping isn't really ritualistic. Cost seemed way to high. Still have stock front seat. They are just taking up space, driver seat is electric, pretty much any positive number $ and the seats are your, just come and get them.