Bottom case compatible with early 2009?

Thanks ! Will try it out.

The late 2006 bottom case only accept logic boards with model numbers 1889-A and 2213-A.

2279-A Logic boards will not fit and have a different/updated bottom case.

Now, what I have is 2496-A. Also, this logic board uses an updated bottom case and will not work with the model numbers mentioned above.

Alvin, that's a very good breakdown of the issue. Unfortunately Apple doesn't state anything so plainly. As you've discovered, the model numbers of the boards are the best pieces of information to go by, since other indicators like 3,1 and mid-2008 are very vague and not necessarily meaningful (thanks for all the confusion, Apple!)