Buescher avoided a multi-truck crash in the closing laps and held on to a 13th-place finish to clinch the truck title by just six points over Timothy Peters, who finished eighth.
Rookie Ty Dillon was running second and trailed Buescher by only one point with less than three laps to go in the scheduled 200-mile race at Homestead. But Dillon wrecked into the outside wall after Kyle Larson bumped into him while attempting to pass for position in turn three. Larson backed it into the wall and then slid down the track before he collected Ryan Blaney. Buescher managed to avoid the crash while he was running in 11th at the time.
"That was close," Buescher said. "Ty and everybody at (Richard Childress Racing) were giving us a run for it at the end. I was trying to get everything out of this Chevy truck, but it wasn't one to go forward. It was maxed out on speed. It was loose, and it was sliding around. I almost went into the wall myself, but I held it together, and everything came our way."
The three-truck crash forced NASCAR to briefly halt the race for track cleanup efforts, and it set up a green-white-checkered finish.
Kyle Busch led the way for the final restart, but Gale pulled even with him on the final lap. Both drivers rubbed with each other while coming out of the last turn, but Gale nipped Busch to the finish line by just 0.014 seconds for his first victory in his 32nd truck start.
"Coming off of (turn) four, that's not my driving style, but it's my first chance to taste a NASCAR victory," Gale said. "I know it's Kyle Busch, but I don't get opportunities like that very often."
Gale became the record-extending ninth different first-time race winner this season. The 27-year-old Mobile, Ala. native is also the 16th different driver to win a truck event in 2012.
Busch was attempting to win his first truck race of the season. He made only three starts in the series this year, driving his No. 18 Toyota.
"It's been a tough year, and it's just the way things go," Busch said.
Joey Coulter finished third, while Buescher's Turner Motorsports teammates, Nelson Piquet Jr. and Miguel Paludo, rounded out the top-five.
Johnny Sauter, who won this race one year ago, took the sixth spot, followed by Parker Kligerman, the pole sitter. Justin Lofton and Ross Chastain finished ninth and 10th, respectively.
Dillon wound up finishing five laps down in 25th. The RCR driver earned rookie-of-the-year honors in the series. He also ended the season fourth in the point standings (-24). Coulter, who is Dillon's teammate at RCR, moved up to third in points (-19).
"It's unfortunate," Dillon said. "We were in a no-win situation. We just had to go out there and win the race and make something happen, and that's what I was trying to do. I knew my guys had my back, and then I just tried to make something happen there at the end. We got to second, and the points were looking good and weren't really worried about that, just trying to win the race. Kyle (Larson) is a great driver, and I know he probably didn't do that on purpose."
Larson, who recently won this year's NASCAR K&N Pro Series East championship, made his fourth truck start. Last week, he finished second at Phoenix.
"It's tough that I got into a point contender there, but I'm also racing for the win," Larson said. "I felt like I had the position going into the corner, and I was down on the apron. It's hard to say. I might have been at fault. It was just hard racing, but it sucks that I took out Ty."
Buescher, in his fourth full-year of truck competition, became the 12th different champion in series history. The 22-year-old is also the second youngest titleholder. Austin Dillon, who is Ty's elder brother, won last year's truck championship at the age of 21.
Buescher, who drives Turner's No. 31 Chevrolet, recorded his first four wins in trucks this year. He also posted 10 top-five finishes and 14 top-10s. Buescher finished third in points last year.
"Everybody on this team has done a fantastic job," he said. "We had a shot at it last year, but we came into this year swinging and did a lot of work during the off-season. It definitely paid off. This is definitely the coolest thing I've ever done in racing."