Abstract: A movable subframe or slider for a tractor-trailer includes a pair of elongated spaced-apart parallel main members and at least one generally K-shaped cross member structure which extends between and is attached to the main members. Specifically, the K-shaped cross member structure includes a base member which extends perpendicularly between and is attached to the main members, and further includes a pair of inclined members, each of which extends angularly between and is attached to a respective one of the main members and the base member. Each of the main members is adapted to be slidably mounted on a respective one of a pair of depending parallel rails of a trailer, and a retractable pin mechanism enables selective positioning of the slider along the rails for variable load distribution of cargo contained in the trailer. A hanger depends from each of the main members adjacent to the ends of the base member for supporting an axle/suspension system.