Bench seat tracks - 2 door to a 4 door

The track overall height, bolts to floor, didn't change. The bolts to bottom of seat and length of travel may have changed. The biggest difference is the shape of the track rails. The earlier tracks had deeper rails with larger rollers and steel roller changes. All of that changed in later models. The roller cages changed to white plastic, nylon, or something, and it would break. Later track design on right of pic should be what you have under a 73 bench. Roller cages shown are from the earlier tracks.