The "68" in the c/n tells us the US year of manufacture = 1968; and it is the 95th of the 98 M20C's built that year. The M20C was a Mk21 with squared off windows and a new front windscreen.
This one popped onto the US register as N6790N and had some eleven owners before being cancelled on 18-05-2011 for its move to NZ where it was registered on 20-06-2011 to the Woodpecker Trust and almost immediately to Hans Holtz of Auckland.
Here is a video clip of it departing Cape May in New Jersey :-