I’m not sure how much a box truck weighed in 1978, but a modern 15-foot U-Haul has an empty weight of 8,115 pounds. So the roof may have required quite a bit of reinforcement to handle that much ...

U-Haul is intended for DIY moves ... A 10-foot truck can fit belongings from a studio or one-bedroom apartment, while a 15-foot truck can typically accommodate belongings from a one- to two ...