And now parking brake issues 66 Dart

Maybe the long cable (the one that connects both sides) is the wrong one? I wonder if Plymouths have a shorter cable to account for the shorter wheelbase. Maybe they sent you that version? Just thinking out loud here.
Thanks for the idea, this is what I ordered. Should be the right one and is actually longer than the old one left over.

Bruin Brake Cable 92622 Intermediate Dodge Plym fits 62-66 Dart MADE IN USA | eBay