Aporte original por: LikeARabbit ,
The two top cases carry different part numbers and don't appear to be interchangeable. I couldn't tell you exactly what differences there are but just looking at a couple of pictures I do see small changes in the structure of the top cases from one generation to the next. [http://d3nevzfk7ii3be.cloudfront.net/igi/s35fTCrZtE3dGoPY.medium|Early 2011 battery replacement], notice the top case ridge to the left of the RAM is a smooth line. [http://d3nevzfk7ii3be.cloudfront.net/igi/6MSUYFmPK6UkdPye.medium|Mid 2010 battery replacement], notice the top case ridge has an extra bump in it to the left of the RAM. Obviously this is just one example but I imagine if you were to scour over the bare parts, side by side, you'd find that there are differences in mounting points, structures, connections, etc.