Abstract: Two first engagement members are formed on a first side of a transmission plate of a dual backset deadbolt assembly, while two second engagement members are formed on an opposite second side of the transmission plate posterior to the first engagement members. A first cam drive unit is retained rotatably in a first backset position relative to the transmission plate and is disposed adjacent to the first side. A second cam drive unit is movable between first and second backset positions relative to the transmission plate and is disposed adjacent to the second side. A deadbolt operating spindle of a lock extends through the first and second cam drive units so as to permit engagement of the first cam drive unit with one of the first engagement members in order to actuate the transmission plate when the second cam drive unit is in the first backset position and the deadbolt assembly is adjusted to a shorter backset length.