It drops out so easy because the trans is computer and vacuum controlled.
You probably won't use a computer in your swap?
Mine is set up so it automatically shifts in and out of OD and lockup determined by speed and not load or vacuum.
Mine is also adjustable, so I can set those speeds.
I can pull a 15% grade in OD and lockup at 75 without any problems at all and not much throttle either.
You can't really base it on how your computer controlled trans in the Dakota operates.