At the published coords you'll find a sign. Find Lucy's number. Label the last 6 numbers ABCDEF
The final cache is located at N50 48.BAC W001 02.(D+E+F)(A+B)(A+C)
You're looking for a small screwtop matchstick holder. It is visible from the ground.
The cache was set without any equipment at all, but you may need something to help you up into the tree from the ground if you're not particularly nimble. There is also a tricky section about half way up. The tree is very snaggy so if you're going to use ropes you may find it harder than usual.