This one is located at Kanab's unofficial used car (and many other items) lot. You can buy just about any type of vehicle - from cars and trucks to ATV and RVs and all sorts of other stuff as well.
The cache is a micro and I think may be a little tough to find (a friend even called it evil) even though it is hidden in plain sight. Thus the higher degree of difficulty. For safety's sake, pull off the highway into the lot to search. You will need your own pencil. Please be sure you replace it carefully.
This is no longer the used car lot but the cache remains the same