in 2013 for Brad Keselowski Racing. At Iowa Speedway in September, Chastain won his first career Truck Series pole for the Fan Appreciation 200; he led the most laps in the race, finishing second to James Buescher as the race underwent a green-white-checkered finish. Chastain also came close to the win at the penultimate race at Phoenix, finishing second to Erik Jones after leading over 60 laps. Years later, Chastain said that he initially made the move to BKR as an attempt to get in a Team Penske ride, but that BKR and Penske did not view the situation that way. 2014–2016 Leaving BKR after the 2013 season, Chastain moved to RBR Enterprises for a part-time schedule in the NASCAR Camping World Truck Series for 2014. Comments before and after the Martinsville race, as well as racing actions during the race, led the team to fire Chastain from the ride. In May, he announced he would make his debut in the Nationwide Series (now Xfinity Series) at Charlotte Motor Speedway, driving the No. 55 for Viva Motorsports. Chastain later drove for Hattori Racing Enterprises at Michigan International Speedway, replacing Johnny Sauter. If that opportunity did not arise, Chastain was set to replace another driver that weekend, John Wes Townley in the No. 5 Wauters Motorsports truck at Gateway Motorsports Park. In the race with HRE, Chastain finished twelfth, which was to that point the team's best finish in NASCAR competition. The finish eventually turned into more sporadic appearances with HRE throughout the rest of the season. Chastain also joined the team for a part-time NASCAR K&N Pro Series East effort that year. He then joined JD Motorsports in 2015, replacing Jeffrey Earnhardt. The opportunity emerged after Chastain raced with TriStar Motorsports at the end of the 2014 season. His car was comparable to the performances of the JDM cars, which led to a deal in the offseason. Chastain logged four top-tens on the year, ninth in the season-opening PowerShares QQQ 300, tenth at the other Daytona race, tenth at Iowa, and tenth at Darlington, and got into an altercation with Ryan Reed after a race at Richmond International Raceway. Reed claimed Chastain made too much contact on late restarts and vowed payback, while Chastain simply brushed the incident off as a difference of opinions in short-track racing. 2017 Chastain's 2017 Xfinity season was the best of his career, scoring a