I added a third row seat into my '00 XC - it is pretty straight forward if you have all the parts. Most parts are visible in the pict above:
- Take all 4 floor boards (two edges and the larger two center) to make sure your carpet matches (if you care about that)
- narrow carpet strips that cover the metal rails in the base of the floor (see pict above)
- small screws that hold the carpet
- seatbelts, seatbelt mechanism bolts
- seat belt bolts to hold the lower belt in to the frame rail that the carpet covers (see pict above)
- two seat belt latches, the bracket goes into the spare tire well - 3 gold colored bolts hold it in place
- plastic "oval" that goes into the back of the seat where the catch level clips when the seat is up.
- light grey carpet "mat" that rests under the seats
- there is a piece of wood that goes across the spare tire hole. I made a false floor below Volvo carpet pieces and used two dowel rods to provide support when the kids climb in. I didn't have Volvo's piece of wood, so I made my own. and its rock solid when the kids climb in and out. I also put a subwoofer below it. My spare didn't fit in the well with the seat belt bracket. If you want a spare, grab the one out of that V70R as well.
I had to trim my light grey carpet to get around the seatbelt catches:
I used a C-clamp to keep the seat belt from recoiling too far back while I bolted the belt in place near the C-pilar:
3rd row is great.. a wagon isn't a wagon without the 3rd row!! My R didn't have it, but we talked the dealer shop into installing it as a selling point. Granted it's a different color (tan as opposed the the charcoal interior) but it's covered up 99% of the time anyways.