Darnell, who gave team owner Jack Roush his fourth truck victory and 17th race win overall on the two-mile Michigan oval, was on his way to what looked like an easy victory until rookie Mark Mitchell scraped the wall and brought out a caution flag seven laps from the end.
That bunched up the field and, when the green flag waved for the final restart with three laps remaining, Benson did everything he could think of to pass the leader. He finally drove his Toyota all the way onto the apron coming off the final turn and nosed ahead, but Darnell also went low, driving his Ford alongside Benson and using a side draft to win by 0.005 seconds -- just inches.
That is the closest finish under electronic timing and the second closest in series history. Butch Miller beat Mike Skinner by 0.001 seconds at Colorado National Speedway in July 1995.
NASCAR officials had to look at photos of Saturday's finish before calling Darnell to Victory Circle.
"That's what truck racing is all about," Darnell said, shaking his head in wonder. "We've had some strong runs this year, but we couldn't pull it off. I just hope this helps us get our season turned around.
"I think the finish was a little more exciting than I wanted it to be. The way these trucks side-draft, I knew he'd be able to suck up to me. That's what he did, but I did the same thing to him and wound up just winning by a few inches."
It was only the third top-10 finish and first win in 10 starts this year for Darnell, who moved up to 10th in the standings. Darnell has won twice in 61 truck races.
Benson, who moved into the points lead, finally saw the replay of the finish and winced.
"Just look at the TV there," he said. "That just hurts, bad. I could say that's probably the first time I've been on the losing end of something like that. I don't know what I'd do if I had to do it again."
There also was a photo finish among the next three drivers, with former Formula One driver Scott Speed, who finished fourth earlier in the day in an ARCA stock car race, awarded third, ahead of Todd Bodine and Brendan Gaughan.
Ron Hornaday Jr., who came into the race leading the points, was spun out by Kyle Busch on the last lap, raising a huge cloud of white smoke that the whole back of the field had to drive through. But Hornaday remained low on the track and NASCAR left the green flag out to the end.
Hornaday, who began the last lap in the 100-lap event seventh, wound up 23rd, the last truck on the lead lap. He fell to third in the standings, with Benson, new runner-up Bodine and Hornaday separated by just 21 points.
After the race, Hornaday and car owner Kevin Harvick sought out Busch in the garage and there was some yelling and finger pointing among the trio before things calmed down.
"He just drove into me because he got mad because I took us four wide and passed him cleanly," Hornaday said. "Halfway through the race, he showed me he was upset because he lifted the back of the truck up. If he is going to race that way, that is pretty chicken. He doesn't deserve to be a racer.
"He has a lot of talent, but that is just flat stupid. ... I don't knock any other driver, but I will tell you what, that kid has just about done wore me out. I don't know if I have to give up this championship to teach him a lesson. I hope I don't hurt him because, if Joe Gibbs lets him do this, I am ashamed for them."
Busch, who got started on another weekend tripleheader with a seventh-place finish, said the bump wasn't payback for an incident this year in Charlotte.
"I just got into him. Sorry about that," Busch said before Saturday night's Nationwide Series race at Kentucky Speedway. "But remarks from Harvick and Hornaday are what they're going to be, they're big mouths anyway and so we'll take it and get on with it and hopefully beat them out for this championship."
DINWIDDIE SEES FLAG MIX-UP AS OMEN
Trucks: Crafton survives wild finish for first win
