Should be an EJ253 (variable valve timing SOHC 2.5).
Wiring into the tailgate fatigues and breaks. If you get any electrical gremlins pertaining to taillights, defrost, rear wiper, etc., pull back the boot where the harness goes from the body to tailgate. Obviously wires can be repaired, but the whole harness from Subaru isn't too expensive (there are at least 3 part numbers, make sure to use your VIN. They were on the shelf at the dealership where I worked).
Rear bushing for the front control arms is now mounted vertically, and has to flex when the suspension moves. Much more likely to wear out.
Any trouble codes will disable cruise control
I don't think a 2006 Base model would have an immobilizer, but double check. If it does, do not loose your last key!