When a previous owner removed the powerglide and replaced it with the TH350 in my 67, they left the kick down uninstalled. I had to buy a bracket similar to the link in post number 2. The stock throttle linkage was fine, but the transmission kickdown needed a "holder" in order to allow for its cable to pull forward when the throttle was "mashed".
Maybe that same previous owner removed (for whatever reason) a stock bracket that was installed for three speeds (used in 68 and above)?
Never argue with an idiot; they'll only drag you down to their level, then beat you with experience.