Factory door moldings or not

I have a 1973 Dodge dart four-door custom and the moldings go from the fender all the way back onto the quarter panels. Look to have a rubber insert the slides in a track but they seem to have shrunk so I’m short about 1 to 2 inches on every molding, the molding track that the rubber slides into is a mounted with about three or four screws in every molding. Any ideas where I could get that rubber in length so I could slide new pieces in