The ones you are showing are 72 belts, all models.

Part #: 9917 HX9 (Black)
Label No. 3670 178
BELT, Front Seat Lap Center Tip Half
3471 = Week 34 1971

Part #: 9918 HX9 (Black)
Label No. 3670 789
BELT, Front Seat Lap Center Buckle Half
5171 = Week 51 1971

Here are the labels from my 70 Cuda seat and shoulder belts. Black buckle & black webbing.