You'll need to befriend someone who owns a B3 CQ and be willing to let you swap said seats out.
I've taken the front seats out of my B3 sedan, nothing to it, to check out why one of the motors were not working. That reminds me, I never put back the motor in question, one more thing in the to do check list!!
The front are too wide to fit the B2 and need to be modded although the rails are the same style. The rear are nearly the same size but have slightly different mounting points. Hope that helps. I have tried to do the same thing but ended up just swapping the seat backs for the front since the bolsters were in better shape and the old drivers seat frame was broken in multiple spots. I am currently devising a plan to wire up seat heaters in the front and the back (84 4kq).
Felix is right, the seats from the B3 are too wide. The only seats that fit native are from B2 Passat (Quantum) and 4000 and VW Fox. I'm not sure about B1 Audi Fox since those are mostly rotted away by now anyway.
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