The Incredibles
At the given coordinates, you will be at a white marker post which contains 2 four-digit numbers.
Subtract the last 3 digits of the Northing coordinates from the first four-digit number, subtract 677 from this total, and this will give you your True heading.
Subtract 1713 from the second four-digit number, and this will give you the distance in feet that you will need to travel.
Now you just need to find the cache!