Is it only on one rear wheel?
The hubs are easy to replace and not terribly expensive. How many miles on them?
Were they hard miles? Seems logical to start there if you don't have another suspect.
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2011 370Z 6MT Sport Gun Metallic | ARC | CJM | Ecutek | FI | Fujimura | R2C | SPL | Stillen | TWM | Z1 | ZSpeed | |