Load King, by Custom Truck One Source, offers a wide range of custom Heavy Haul trailer designs with options to meet virtuall ... y any construction or general transportation-based need. We have the experience and skill to know what it takes to engineer and manufacturer an efficient, safe, reliable, well-built trailer. About Custom Truck One Source: Custom Truck One Source is the first true single-source provider of specialized truck and heavy equipment solutions. With sales, rentals, aftermarket parts and service, equipment customization, remanufacturing, financing solutions, and asset disposal, our team of experts, vast equipment breadth and integrated network of locations across North America offer superior service and unmatched efficiency for our customers. read more