The process to get the classic look is pretty easy.
Head over to WonderHowTo for the full guide.
How to Make Yosemite Look More Like Classic, Pre-Mac OS X Systems| WonderHowTo
Give Yosemite a Classic, Pre-OS X Look By Tweaking These Settings
If you find yourself yearning for the old days of OS 9, WonderHowTo shows you how to give Yosemite a classic black and white look by tweaking just a h
