1972 Duster lockstrip??

I decided to replace my crappy pitted windshield and I spoke with a (self described) tech at Classic Industries who swore I would require a lock strip to go with my windshield gasket. I also purchased a gasket for the rear glass because it leaks. Again, I was informed that a lock strip was required. I started pealing back the windshield gasket today and I do not see a lock strip. A quick perusal of this site showed a lock strip required for a 1967 Barracuda, but not much info on a 1972 Duster.

Q-Do I need this lock strip for my windshield/ rear glass gaskets? Did they not come originally on this model? Is it useful to install them even if they are not original?

Thanks for any info you can provide.