68 and 69 A and B Bodys use the same seat frames.
Risers are specific to A and B and do not interchange. So yeah a 69 Charger bucket will fit a 68 Dart as long as you use A Body risers and vice versa.Seat back release knobs are different between years but interchange.Seat backs,hinge covers,headrests and hardware all interchange .


"Long Live Mopars"