This is a simple offset multi.
At the posted co-ordinates you will see an interesting inscription embedded in the wall. It is large, it contains a message and has a date.
Using the date:
A=The third number in the year
B=The second number in the year
C=The first number in the year
D=The month divided by 2
E=The fourth number in the year multiplied by 4
You will find the cache at: S 38 06.ABC E 144 03.DDE
Checksum - S=27 E=28