The Kyle Busch Motorsports driver took first from the outside lane on a Lap 191 restart in the Texas Roadhouse 200.
“It’s really tough racing against these veterans,” Gragson told FS1. “You can’t pass on the outside at Martinsville, but I did it.”
Gragson, 19, celebrated by climbing the fronstretch fence at the 0.526-mile oval (and then vomiting after his descent).
“To be racing here in the NASCAR Camping World Truck Series, it’s a privilege,” he said after the fourth top five of his rookie season. “All those hours of hard work, I knew to myself this morning, I knew I could get it done. I’ve known it this whole year and I told myself I’m going to get that trophy today, and that’s what we did.”
Crafton finished second, but the playoff-eligible driver said it was “salt in the wound” after losing the lead on the restart. The race is the opener of the Round of 6 that will determine the four drivers who advance to the season finale at Homestead-Miami Speedway, and a victory would have put Crafton in the championship four.
“(Gragson) had a perfect restart, and I sucked,” a dejected Crafton said.
Johnny Sauter, also in the playoffs, finished third.