This paper reports the correlation of truck interior noise, near the driver's right ear, between driving on road and while operating on a dynamometer. It was a critical benchmark in the commissioning process of a heavy-duty truck anechoic chassis dynamometer. It required road load data to be gathered on a Proving Ground, using the Coast Down procedure detailed in SAE J2263 OCT96, and then simulated, while operating the same test vehicle on the dynamometer, using SAE J2264 APR95. The criteria for interior noise comparisons were typical Class 8 driving scenarios: constant high gear cruising, full power single gear acceleration runs, and engine braking. The analyses using these SAE standards, together with the final correlation results, are presented and discussed. A footnote is the unique challenge of Class 8 testing versus SAE coast down procedure, since truck transmissions must not be tested in Neutral, per SAE protocol, to avoid damage.