Larry,
It would be nice to know the specifics on your truck. Especially the Vehicle year and transmission.
Mine is a 2012 2500 CC with a 68 RFE.
As an Emergency measure, in your owners manual there is a section that covers 'Unlocking" the transmission when "Stuck" in PARK. Small screwdriver, inserted gently up into the steering column bottom hole you will feel a slight spring loaded resistance. Depress gently, move shifter to Neutral, start truck and shift normally to Drive or Reverse, and continue driving.
Sounds to me if you are experiencing this and if your truck was subject of the Recall and it wasn't done, this could be the issue. If it was done it may be improperly adjusted, failing again or the BTSI needs replacing.
****One Note: I understand when the dealer does the BTSI Recall or replacement, there is a step by step procedure that must be followed. If any steps are short cut or not completed you will possibly end back in the same situation.
~Chad