Vent window seal difference?

My 1973 plymouth Valiant needed new vent window seals, every one that I searched said 1967-1972, I could never find any that a for later years. I ended up purchasing these and they are made by Metro. They kind of fit the same but they don't seem to create an air tight seal.

Is there a difference between 67-72 seals and later year vent windows? If so where do you find them for 1973 and up.