I am assuming you are speaking about the vinyl door panels? I have found that the panels from the back doors work well on the back doors on all models (140 and 160 series) up through 1975, all years being interchangable.

If you look closely at the front door panels on the earlier ones, up through 1973 I believe, you will see that the part closest to the dash slopes downward slightly. While you can still use these on later models, there is a metal support tab that sticks up from the door panel and it is exposed if you use earlier panels on a later model year Volvo. I remade my door panels, cutting new board etc, and just used the metal strip at the top of the door panel on my new ones. They turned out great.
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1975 Volvo 164E - 86,000 original miles