Transit agencies continue to be the focus of heavy-duty diesel engine emission reduction programs by using Federal regulations as well as self-imposed mandates to reduce smoke and particulate emissions. Such is the case with the Miami Valley Regional Transit Authority, which wanted to characterize the emissions of a 1985 model year Detroit Diesel Corporation (DDC) 6V-92 TA diesel engine that was rebuilt using DDC Upgrade Kit 10-B. In addition to determining the baseline exhaust emissions from the upgraded engine, two separate emission reduction technologies were evaluated. The first system evaluated was an electrically regenerated particulate trap oxidizer developed jointly by Donaldson and 3M The second technology evaluated was an ethanol injection system in conjunction with an oxidizing catalyst designed and manufactured by Midwest Power Concepts (MPC) Emission tests were performed in accordance with the heavy-duty diesel engine transient Federal Test Procedure (FTP). Transient test results, reported in grams per horsepower-hour (g/hp-hr) for each configuration tested, include emissions of hydrocarbons, carbon monoxide, oxides of nitrogen, particulate, and aldehydes. Baseline engine-out emission levels of the upgraded DDC 6V-92 TA engine were well below the target of 1989 model year certification levels. The particulate emission level of 0.11 g/hp-hr approached the EPA 1993 urban bus standard of 0.10 g/hp-hr. The Donaldson trap system was effective in further reducing this particulate level by about 50 percent. The MPC ethanol injection/catalyst system was also effective in reducing particulate emissions by almost 50 percent, but with a penalty of increased organic material hydrocarbon equivalent (OMHCE) emissions. Oxides of nitrogen (NOx,) emissions were somewhat lower for both the Donaldson trap system and the MPC system when compared to baseline levels.