I am not familiar with the AT linkage used on the 74 Dart, but I imagine it might be similar to other Dodge products of that era. I had two 67 Dodge Coronets that had the AT linkage with alternate pitch threads at each end (so the rod would not loosen nor tighten if either locknet came loose). The linkage was attached to the firewall and the intake manifold. I experienced similar problems as voiced by the lady on your show and it was due to a broken motor moount. Given the age (38 years - of the Dart - not the lady!) and that motor mounts are not considered routine replacement items nor frequently inspected, I suspect the problem may be more likely caused by a broken motor mount rather than a misadjusted shift linkage. Having the linkage attached to the firewall is what disturbs the geometry (and effective length of the shift rod) when engine torque causes the engine to rotate adversely due to the broken motor mount. Trying to get into Park could be an issue with the motor running as you have to shift into Reverse enroute to Park, and this would create a couple (locking the back of the motor-AT tripod mounting system) thus allowing the motor to rotate and change the effective length of the shift rod. The problem could be the shift rod adjustment, but I'd say it's less likely than a broken motor mount.