Exemplary vehicle truck bed assemblies may include a unibody construction. A cargo box of an exemplary truck bed assembly may include at least two different floor-to-side wall mating configurations, and each of the at least two different mating configurations is non-visible from within a cargo space established by the cargo box. In addition, each of the at least two different mating configurations may include a fastener, such as a weld, an adhesive, and/or a bolt, for adjoining adjacent mating surfaces of the cargo box floor and side wall.