The cache is not at the posted coordinates.
Imagine that you're the commader of two remote observation posts along Mitchell Road. You have spotted a band of geezers coming toward you up 6.5 Road, and you believe you've spotted the notorious Over the Hill Gang, looking for a place to stash their loot. The geezers stop and appear to be hiding their loot in a cache! Using your transit theodolite, you first shoot the North Star and then the angle to the geezers from each of your outposts. Using the two bearings from true north to the geezers' cache, you are able to calculate the exact coordinates and find the loot using your GPS receiver! When your mission is shut down, the last thing you do is hide a cache at each of your outpost locations. You call your caches Outpost1 and Outpost2, and inside each Outpost cache, you put the bearing from true north to Over the Hill Gang inside. That way, if you don't make it back to the area, others will be able to find this cache of ill-begotten loot.
The two outpost caches must be found before the real coordinates to Over the Hill Gang can be determined.
There are many GPS devices that will calculate The Intersection of Two Lines. If you don't have one of these devices, there are many Apps and websites that will do the same thing for you. Search terms: triangulation, spherical trigonometry, halversine, spherical law of cosines.
Check out www.GeocachingToolbox.com and www.movable-type.co.uk/scripts/latlong.html and the Android app named GCC from Google Play.
Mitchell Road runs along the base of the Bookcliffs between 201Rd (Baxter Pass) and Hwy 139 ( Douglas Pass).
This is High desert terrain. It's blazing hot in the summer so take plenty of water for these hikes. The roads will be a muddy mess when wet and a 4x4 is recommended. When storms are in the area avoid dry washes because of the danger of flash flooding. If you are unfamiliar with this kind of enviroment, talk to locals before venturing out.