SHOP OPERATIONS How to assess replacement parts Insights and guidelines to help fleets choose the right type of part for the right situation, keeping both uptime and the bottom line in mind. By Gregg Wartgow [ PARTS ] 30 Fleet Maintenance | July 2019 T here are three general categories of replacement parts: genuine OE, aftermarket, and remanufactured. Achieving two of a fleet's most critical goals - vehicle uptime and expense control - requires an understanding of all three categories, along with what makes one a better option in certain circumstances.