I recently went in on a group buy for the MAB project. I received three boards and only need two for my K2's. I did assemble and test the third board if anyone is interested. It does not include the Internal Mic Adapter but you could add that yourself by removing 4 zero ohm resistors and adding the IMA parts.
To install you need to plug the board into the mic header on the front panel board and solder four wires - 3 to the front panel board and one to the control board. The MAB gives you a fixed audio output (W3FPR circuit), a key line and a CW tuning indicator (K6XX circuit). See
http://www.genebitsystems.com/david/K2MiscAccessoryBoard/index.htm for the MAB details. The MAB was designed by KW4M and is a very nice addition to the K2.
I will sell for $30 shipped via priority mail to the lower 48. I can be reached at my call @ arrl.net.
Lou W2ROW