Compatibility for case pieces between A1278 models?

I bought a 13" unibody MBP not too long ago, and it runs well, but the casing is in rough shape. There are scratches all over the lid and the bottom, the keyboard is dirty, and the bottom cover is held on by just one screw. I'm trying to find a for parts MBP that I can salvage the casing from, but I'm not having any luck finding the same model as mine. What I need to know is, are A1278 parts compatible across the board? Could I buy an aluminum 2008 MacBook and use the casing from that? Or am I restricted to the same exact model as mine?

Thanks.