Final answer:
An exhaust leak that is discharging to the atmosphere and a leak at the exhaust stack behind the cab would fail an annual inspection for truck exhaust system issues.
Step-by-step explanation:
An annual truck inspection may fail if there is any exhaust leak that is discharging to the atmosphere. This means that any leak that allows exhaust gases to escape into the air would be considered a failure. Additionally, a leak at the exhaust stack behind the cab would also fail the inspection as it is still part of the exhaust system.
However, a leak 15" or more forward of the rearmost part of the cab would not result in a failure, as it is not a part of the exhaust system that is covered by the inspection. Similarly, a leak that is forward of or directly below the driver/sleeper compartment would also not cause a failure as it is not within the scope of the inspection.