At the posted coordinates you will find a cover in the middle of the sidewalk. On this cover is a large word in the middle.
Convert the first letter of the word to a number (A=1, B=2, etc) and call it X. Let Y and Z both equal 0.
Add XYZ to 289 to get the last three digits to the West coordinates.
You will find the final at: N 42° 44.673' W 83° 22.(XYZ + 289)'
Good luck and have fun