Efficiently solving the truck loading problem (TLP) is crucial for achieving urban logistics objectives. Many heuristics, mainly based on wall-building and layer-building concepts, are presented in literature to solve this NP-hard problem. The current research presents a two-step novel prioritization-stacking heuristic algorithm for solving the TLP. The new algorithm primarily aims to improve the truck space utilization and reduce inventory costs at origin and destination points. In particular, the current work considers developing countries conditions in which demand is uncertain, cost minimization is prioritized over customer service, and routing optimization is complicated by a lot of traffic jams. The performance of the proposed heuristic is evaluated by applying it to a real-life case study from the Jordanian market. Additionally, the stacking part of the proposed heuristic is benchmarked with a literature data sample. Both implementations have proved the validity of the suggested heuristic algorithm.