Thanks, this should help.Your Outback is ten years ooder than mine, but it’s probably quit simliar. It shouldn't be all that hard to do, removing the lift gate panels to access it may require a panel removal tool (not expensive). I had to replace my wiring harness and there are threads that tell how to remove panels on the 08 model. Follow this link;
https://www.subaruoutback.org/threads/2008-outback-rear-wiring-harness-replacement.411058/ There are a few diagrams showing how to remove those panels. Once in there, should be straight forward, disconnect plug and unbolt it.