2003 Infiniti G35 The left front wheel "rattles"

Noises problem
2003 Infiniti G35 6 cyl Automatic 122000 miles

I have been hearing a rattle in the left front wheel-area anytime I hit a bump or drove on a rough road (we live on an oil-chip road and it rattled at any speed, turning the wheel either way or continuing straight). We recently changed the tires but that did not improve the rattle ($500+). The mechanic suggested new shocks and struts should get rid of the problem ($800), but all the new shocks and struts did was lessen the frequency. Now that wheel only rattles when a bump or chuckhole is hit with that wheel; the noise has lessened significantly on the oil-chip road. Anyhow, the mechanic says it is either the bushing or the entire "arm" but he doesn't know until he takes it apart. I took it to a reputable shop - all of their other work has been excellent and reasonable in cost. Even the dealer doesn't know what the problem is and wants to tear my car apart to look at it, but every other rattle I've taken the G35 in to the dealer for has been dismissed as I'm "hearing things."