The trailer hitch receiver broke off the trailer hitch frame, which caused out travel trailer to become completely disconnected from the truck. The hitch was standard equipment on the truck when we bought the truck new, and the hitch is rated as ‘Class III’, which means it should be able to tow a trailer weighing up to 8,000 pounds, with a tongue weight up to 800 pounds. Our trailer has a dry weight of 3,500 pounds, and a hitch weight of 535 pounds. We’ve owned the truck since it was new, and the truck has never pulled a heavier trailer. By a stroke of incredibly good luck, the trailer broke free from the truck when we were going 5 mph in a level parking lot. We were 1450 miles into a trip, and many of those miles were at highway speed. If the trailer receiver had broken at highway speed, the trailer would have been completely free of the truck at highway speed.