4.2l Engine Interchange Issues??
 

Hello, I am trying to swap out a 2008 S5 engine for a late 2009. It is not listed as interchangeable. I have the wiring loom and ecu. The two wire plugs that connect to the vehicle have all the same pins. The connections for the fuel seem connectable as do all the mounting points. The transmissions are the same and geared the same so i was going to swap that too. What is the problem? Anybody know??
In advance, Thank you for you time : )