Spilt a fizzy drink on the keyboard and need some information.

Hi

I Recently spilt a fizzy drink over the keyboard area of the MacBook Pro and found out that i need to replace the whole unibody which will cost me £200+ to have repaired through apple. Im willing to put the work in myself and replace the whole unibody but cannot find the right unibody for my MacBook. Im confused with what model i actually own. Can someone help me identify what unibody i need to purchase.

I have gone through the "ID my mac" and the result came back as following;

You have a 2.8 GHz (Mid 2009) MBP Unibody 15"

But finding the right unibody is confusing as there's a few models available.