its legit, but you get what you pay for. tons of people have done this before.. theres at least 30 threads in the 83xx forum about this very topic, with pictures.
I changed my housing from sunset red to all black on my 8320 without any problems or issues. I ordered it from ebay (cant remember the seller) but it fit like a charm. It gave me the feel of a brand new BB. I say go for it!