Good morning!
Apple's policy for the Unibody displays is very frustrating. They consider the entire display assembly as one non-user replaceable part. Therefore, I am unaware of an actual apple part number for the display housing, and the only place I can think of for finding one is eBay (maybe even scavenge a good housing off a cheap non-working display assembly?).
Also, I am unaware of any cross-compatibility between machines. The MacBook Air only comes in 13", so it is definitely incompatible.
Sorry for the bad news!