Whats the difference in the doors?

[atm70chevy]

I am needing to replace the doors on my 70 stepside and I've looked in several catalogs and they list 67-71 doors together and 72 doors separately. I think I have found some used doors on Craig's list but I want to make sure they will fit. Is there a difference in the doors from 67-71 to 72 or will a 1972 door fit on the earlier years? Is there a way to tell what year truck the doors came off of? Thanks for any help yall can offer.