Those plastic threads always break. I did similar to you, but not threaded. I just cut a tube (1/4?) the length to set the cable where the plastic threads did, with an axial slot to slide it over the cable. I angled the slot so the tube won't easily fall off the cable, though the cone-shaped seats tend to hold it in place, as does the spring tension.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans