I am swapping out a 2.5 engine from my 2005 Legacy Outback. I bought a used engine from a 2005 Legacy. I noticed the intake manifolds were different, the old engine has a slanted intake (connection to filter) but the new engine has a more horizontal input. No big deal, I hoped. The other big difference is that there are no O2 sensors, nor a place on the wiring harness for them on the 'new' engine.
It seems likely that I should take the intake manifold and wiring harness off the old engine and put it on the 'new' engine because my car will expect the O2 sensors. Do I have any choice in this matter.
Also, why would there be a difference? Different emission standards?
Thanks.