For the 47-50KF and 51-5K mats, they are one piece and cover just the front of the floor pan. The rear seat floor used a carpet that is sold separately.
The HJ mat is 2 peices, one large from mat and one smaller to fit the rear seat floor.
As Gordie mentioned, throw mats were a dealer add on thru their own jobber, or a Western Auto (etc) purchase.