Proceed to the posted coordinates and enter the post office.
To obtain the last three digits for NORTH (N 34° 26._ _ _ ), simply follow these instructions: Proceed to the set of post office boxes on the far RIGHT. Take the number from the box at the top right and ADD 371. The sum will give you the three digits you will need for NORTH.
To obtain the last three digits for WEST (W 088° 39._ _ _ ), simply follow these instructions: Proceed to the set of post office boxes on the far LEFT. Take the number from the box at the top left and ADD 347. The sum will give you the three digits you will need for SOUTH.