I know it is very late, just came onto this topic looking for support on fitting the rear bench of a B8 in a B6.
To confirm:
- Front seats fit. Same rails, same mounting.
- Front power connector doesn't need modifications, except for cutting the locking clip. Otherwise, it slides in with some force, but the wiring is plug and play. Even the rear footwell illumination works.
- Front airbag connector can be swapped with your old B6 ones - the wiring is the same (black/blue/brown). No errors on VCDS.
The rear is different. The back rest will fit, after hammering the center pivot a little bit towards the left hand side of the car. Still, the 60% piece will fit snugly and wrinkle a little bit on the headrest side. The back rest won't clip on the B6/7 bolts, so you'll have to fabricate custom supports to lock them in place. The luggage cover mounts are slightly off-set, and will require drilling on the luggage cover itself (it's riveted in, and after drilling, they can be moved to fit and re-riveted).
The mounting clips of the seat are on the same location as the stock B6/7 clips, and clip right in. However, the rear seat sits VERY tightly and wrinkles under the stock B6 side bolsters, and should classify as doesn't-fit-without-modifications. Additionally, the center seat belt doesn't clip in - it's slightly wider than B6/7 seat belts. Also, the whole seat is a tiny bit smaller than the B6/7 and leaves (small) gaps where the body of the car can be seen. If your seat has ISOFIX slots, they will clearly show and expose any lower metal. Some plastic covers should be advised. On the B6/7, the ISOFIX braces are just wedged in between the rear seat/back rest.
