1965 Dart GT: help on diagnosis?

Welcome. I believe the 64's were cabe operated push button. The 65's were lever or floor shifter operated with a dual cable and 66 and newer were linkage operated. Fyi. If you have a HP 273 they were Charger 273's in the Dodges and Commandos in the Plymouths. Super Commandos were 426 wedge engines in the early 60's B bodies.