RWD sequential gearboxes RD905 5 Speed rear wheel drive transmission. Adapt the RD90 to virtually any engine/car combination without need for new patterns or extensive redesign RD906 6 Speed rear wheel drive transimission. Adapt the RD90 to virtually any engine/car combination without need for new patterns or extensive redesign. RDT 175 5 Speed rear wheel transmission. The Tractive RDT175 combines proven technology from the RD90 gearboxes with a slimmer and simplified housing design.