Upon arrival at GZ you will be at the site of of where the school that served the Sheffield, IL area was. Though now you'll see two baseball fields, a flagpole and plaque remain as a memorial to the former school. The plaque has the information needed to solve for the coordinates for the final.
The final stage coordinates are:
N41 21.1AB
W089 43.7CD
A= 5th row, 1st word, 6th letter
B= 6th row, 3rd word, 2nd letter
C= 3rd row, 6th word, 3rd letter
D= 7th row, 1st word, 6th letter
The code can be cracked using the following sequence: A=1, B=2, C=3 and so on.
Final is within walking distance from where you are starting.
Cache has been placed with knowledge and permission of the Village of Sheffield.