In “The Retrofit Puzzle: Optimal Fleet Owner Behavior in the Context of Diesel Retrofit Incentive Programs” (1) an integer program was developed to model profit-maximizing diesel fleet owner behavior when selecting pollution reduction retrofits. Fleet owners acted in the context of potential government programs including various mandates and financial incentives. Fleet size and the miles remaining for each vehicle were treated as fixed and known at the time retrofits are made. Retrofits were assumed to take place in the present, but benefits and costs are distributed over time. The model was intended as a tool both for fleet owners and for government administrators. In this paper, the model is expanded to allow for retrofits at multiple stages in time. This enhancement enables the model to develop multi-year strategies for retrofit implementation, a capability that is especially important when changing government regulation and incentives, vehicle availability, new retrofit technologies, or other factors make spacing retrofits out over time the most profitable option. A case study is used to demonstrate how a sample fleet owner would respond to various incentives. Potential directions for future research are discussed.