Help with EEC IV serial numbers

Looking to replace my A9P with an A9L, but I'm not sure which serial number I should be looking for, or if it matters.
For example:
NAPA has an E9ZFAA, F3ZFDA, and F3ZFDB available which are all 5.0, 5 spd, mass air ecu's. Does it matter which one I get?
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