Replace Plastic Back of iPad 3 Black?

[10sne1]

The black plastic covering the aluminum skin on the back of my iPad 3 Black (MD368LL/A) is cracked.
I am having some difficulty looking for replacement plastic and instructions.
Thanks

 

[10sne1]

Found the KHOMO Backshell !!

I found the back case. The problem was it was part of a Wilson's leather case. This is the black plastic backshell by itself
http://www.amazon.com/gp/product/B004YWIJSA/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2ZORVN37M8V52