Flat towing 65 Barracuda

I just checked the service manual and here is what it says.

Transmission Operating Properly: The vehicle may be towed safely in N (neutral) at moderate speeds. For long distance towing (over 100 miles), the propeller shaft should be removed.

Is the propeller shaft the driveshaft then?

Yes it is.
And they are right about not towing without it being disconnected.