The coordinates will take you to a sign at Stage 1. Use the information on the sign to find the coordinates for the final stage. We highly recommend that you use the trailhead waypoint to access the final, which is a magnetic keybox.
The final stage can be found at:
N42 04.410 + A + B
W086 30.480 - X - Y
A = Joe and Ruth Hanley were assured that their house would stand for at least how many years?
B = The number of homes that used to be along this stretch of Lakeshore Drive
X = The last two digits of the year when the events described on the sign took place
Y = The day in October that Joe Hanley noticed cracks in his living room ceiling