The 1970 and 71, I think on both had plastic backs and the 1972-73 didn't. I have a set of 1973 buckets in my 1971 Duster, the 72 and later seats are around 7 lbs each lighter than the 1971 I messed up on my car , I ordered the seat covers, headliner and door panels for the 1971 Duster, I should have ordered the 1973 seat covers instead I had to have the local shop that installed the 1971 seat covers make a back for them, the material and color didn't match of course