I would guess it a front one going.
Have you driven the car on a flyover like changing highway's. While going fast make small direction changes and see if the noise changes.
When my fronts were bad, I would get a shimmy in the steering wheel like a tire out of balance...but only on some types of pavements. Further down the same highway, it was fine.
178,000+ miles, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
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