The back seat is different on 70-71 due to seat belt location, if you use the panels from a 70-71 there will be a mismatch at the seat bottom
They are also different at the bottom where the 1974 panels slide in beside the seat belt assembly. 1970-1972 units will not do that. You can still make it work though.
Oops I forgot about you having rear seat delete, then the only problem you will have is the post that stick up that hold the seat belts on the side behind the surround area, cut them off if you havent all ready and 70-71 will fit just fine and not have holes in them for seat belts