yes it will fit... you can total use it...
Anything can be done with a welder, but the bolts do not lineup.
There are 4 listed in the Toyota Handbook, all for 'theft deterrent system' in main fuse box (large lid in centre of dash). First try 2nd row up, 5th from left (Dome fuse). Also 2nd row up, 2nd from right. Also bottom row, 2nd from right. Lastly, 2nd from top on right hand side.
To lay the second-row seats of a Toyota Sienna Limited flat, locate the release lever or button on the side of the seat. Pull the lever or press the button while gently pushing the seatback forward until it is flat. Ensure the headrests are lowered to create a more level surface. Repeat this process for the other seat if necessary.
Do you want to REMOVE it entirely from the vehicle, or are you asking how to lay it down flat in order to make a longer rear deck floor?
You can either slide the third row seats forward with the adjuster bar under the seat or fold and flip the seats forward so that they rest against the 2nd row
On a 2003 Ford Expedition : The 2nd row seating would be a bench seat
In my dodge 99 the 3rd row seat can go in the middle row.
seat belts have a unlimited warranty. the belt gets twisted and they replace for free!
in the fuse box middle row closest to seat 10amp
In the floor behind a flap between the drivers seat and the first row of seats
Any seat could work with safe installation...welding is the most solid way to add seating. You can purchase extra seating online. One site I know of is www.littlepassengerseats.com
The Toyota 4Runner typically seats five passengers, but an optional third-row seat can increase capacity to seven. The standard configuration includes two front seats and a rear bench seat for three. The availability of the third row depends on the specific trim level and options chosen.