Anything's possible with enough time and money... Does the 2009 currently have the I4 or the V-6? The 2006 Avalon only comes with the V6. Transmission in the 2009 would have to be compatible with the new 2006 engine, as would the ECM, Sensors, and the Engine wiring harness at the very minimum. Is there a particular reason that you don't want to repair the blown head gasket? Are you after more power?