Seat Base Installation instructions 
(Install is about a lazy hour and one to two beers depending on hot it is. Can be done in less than 30 mins with a few under your belt - Installs that is!!

)
Remove the original seat and base. You will need a TORX 55 (or 55-PLUS) and a 15 mm wrench in addition to a few more normal tools.
Disassemble the seat from the original base making sure to disconnect the seat sensor wires.
Feed the seat belt sensing wire back down through the carpet/mat and pull it back so it comes out the seam between the front carpet and back carpet. It is attached to a wire that runs across the van right behind the front seats.
Place the new seat base over the studs. You will need to cut a molded carpet (if that is what you have) so the base sits flat. To do this, mark the carpet for cutting just inside the foot print of the swivel floor plate. By cutting the carpet slightly inside the perimeter of the floor plate allows the floor plate to capture the carpet for a more finished look. I use pieces of this cut out carpet to fill the spots which are not covered by the swivel floor plate. (see pics below) These are usually crescent shaped pieces at the front and rear stud/bolt locations. Carefully using a bit of hot glue with the filler carpet pieces can make it look nearly seamless. This approach allows the floor plate to sit flatly on the floor insulation under a carpeted van.
For a cargo mat type flooring, you do not have to deal with cutting as the seat base will sit flat on the floor.
Now that the carpet/mat is dealt with, it is time to route the sensor wires to work with the new swivel base. On the passenger side the wire needs to pop up through the carpet just behind the rear edge of the floor plate. (see pic below) Cut an X in the carpet large enough to feed the connector and the wires up through the carpet/mat. On the driver side, the wires can be fed up through the hole in the floor mounted part of the base. The driver side swivel is raised to accommodate an under-driver seat module that is present on some vans. If you have this module, you may have to remove the plastic cover to allow for the driver seat base to sit properly on the floor and clear the module.
At this point, you are ready to bolt the seat base to the floor. Make sure it is sitting pretty flat. If necessary, remove some of the insulation padding. There should be enough threads on the studs to thread the nuts, and sufficient length on the TORX 55 bolts to reach the threads in the floor. Secure the base to the floor making sure the wires are not pinched or caught under the seat base floor plate.
The sensor wires should be protected with split loom or something similar to prevent chaffing.
On the passenger side, the wire is run inboard of the swivel drum. On the driver side comes up through the whole in the lower section.
Disassemble the connector on the wires coming from the seat. (Others have cut the wires and re-spliced, just be careful and make sure the ignition is off and key removed). This is needed to feed the wires through the small hole in the upper plate of the swivel seat base. Mark the wires before disassembly so they can be put back in their correct positions.
Now you are ready to mount the seat to the swivel base upper section. The studs from the seat base tracks should line up with these holes. IF THEY DO NOT LINE UP

– this means the tracks have moved independently from each other. Realign the tracks by pulling up on the seat slide adjustment bar and move the tracks so they are in proper alignment. Once the studs drop through the holes, secure the seat to the upper section of the swivel base with the original nuts.
Now we can finish the wiring - Pass the two wires through the hole in the upper plate and reassemble the wires into the connector housing and reconnect the two housing pieces.
To Swivel the seats: Typically, what I have to do (for 180 deg swivel) on the passenger side with stock cloth seats is:
1. Tilt the seat back all the way forward, arm rest up.
2. Slide the seat forward most of the way, there is a point which allows the seat to rotate towards the center of the van with the seat cushion just brushing the engine cover center console. After the seat base clears the center console, the seat base can be slid all the way forward and the arm rest will brush the door panel as it completes the 180 (the door does not need to be open but if it is just opened a bit it can make it easier).
3. After rotating 180, slide the seat all the way back and adjust the seat back recline to desired comfort.
Takes me less than 15 seconds.
Driver side is much the same.
Pictures

of finished installations (because I will get

:, if i do not post at least some pictures) -
Passenger from rear looking forward. Connector comes up just behind floor plate and runs inboard of swivel drum.
Passenger at the front looking toward passenger door. Wires from seat come down through the upper section and connect below it. Split loom protects the wires.
D
river from side - Wires come up through hole in lower section and down through hole in upper section. Connection is in between.
Driver side from rear. Note molded carpet filler pieces.
Passenger from side looking toward passenger door - Note the carpet filler pieces for a molded carpet.
Connector from seat on 2002 model year. Model year around 2006 changes somewhat