The posted coordinates will take you to a utility pole, which is the starting point for this and the other two multis in this trio.
This multi should be easy peasy.
On the utility pole, you should find a six digit number oriented vertically under the letters "UD". Reading from top-to-bottom, call this number ABCDEF.
To get to the final stage, go to N 38 39.DB(C+D) w121 19.(A-B)(E-D)D.
These are the other two caches in the trio that have the same Stage 1:
GCB1R95 (Projection)
GCB1R99 (Averages)