It will all physically bolt in. Though you wont be able to use the AVCS in the 2005 WRX motor. And you'll have to transfer your intake manifold over to the 2005 motor so all your engine wiring plugs in.

And you'll need to change the rear diff to 4.44 ratio to match the 2005 gearbox.

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RS Liberty - Because WRX's are only good for parts...