Owners of the 2012 Chevy Caprice have complained about a belt squeal noise and/or crankshaft balancer wobble. It is important to confirm that the vehicle you are repairing does not suffer from these issues, so if you have the vehicle in for other repairs and you witness a belt squeal, you should inform the customer about the possible issue. Follow this link to see what you should do if presented with these concerns.
Source: http://www.autoserviceprofessional.com/article/100422/checking-crank-pulley-runout