This paper discusses the process used for dedicating an Alco 18-251-F commercial diesel engine for nuclear standby service at Pacific Gas and Electric's Diablo Canyon Power Plant. Completed in 1993, this project was the first commercial grade dedication of a complete diesel generator system under the guidance of the Electric Power Research Institutes (EPRI), “Guideline for the Utilization of Commercial Grade Items in Nuclear Safety Related Applications (NCIG-07)”, Reference 1. All four dedication methods outlined in the guideline were used in this effort, including Special Tests and Inspections, Commercial Grade Survey of Suppliers, Source Verification and Acceptable Supplier/Item Performance Record. The complexity of the dedication effort resulted in extensive review and inspection by the Nuclear Regulatory Commission (NRC). Resolving NRC concerns required significant on-site testing (including a 200-hour run of the diesel) using a load bank capable of simulating both resistive and reactive generator loads. In addition, an extensive inspection of the diesel including removal of several power assemblies (cylinder heads, pistons and connecting rods) was required to ensure that the unit did not experience any excessive wear or premature failure of components during the 200-hour run. Engine operating parameters were monitored and analyzed to further ensure that the engine operated properly.The dedication effort resulted in satisfactory completion of the required start-up and post-modification testing within the available refueling outage schedule window. Details of the commercial grade dedication approach, testing, and inspection requirements are presented.