On the 06' you will need a Medallion depth module and the transducer. I believe it is a Lowrance transducer, I'd have to look up which one.
The transducer plugs into the depth module, and then the depth module plugs into the Medallion MMDC already installed in the boat. This will allow you to display depth on the multi-function display underneath the tach.
http://www.mastercraft.com/teamtalk/showthread.php?t=33053 That is a good thread that we posted a lot of photos in. Relates to an 06' 197, but should transfer and apply to the 06' X2 as well.