Brad Keselowski is waiting for a ruling of his team's appeal of a severe penalty handed down after the NASCAR Cup Series race in Atlanta, but the public still doesn't know what it was for.

Brad Keselowski's #6 RFK Racing Ford Mustang allegedly had an illegally modified part during the Atlanta Cup Series race.

Brad Keselowski's #6 RFK Racing Ford Mustang allegedly had an illegally modified part during the Atlanta Cup Series race. (David J. Griffin/Icon Sportswire via Getty Images))

Keselowski was docked 100 driver points, 100 owner points and 10 playoff points while his crew chief Matt McCall was suspended four races and fined $100,000 for allegedly modifying a standardized part the #2 RFK Ford Mustang.

What that part is has yet to be announced, apparently due to the ongoing appeal. The Associated Press reported that speculation surrounds the rear bumper, but that has not yet been confirmed.

Keselowski is part-owner of the RFK Racing team.

Keselowski is part-owner of the RFK Racing team. (Jeff Robinson/Icon Sportswire via Getty Images)

The penalties dropped Keselowski to 35th in the standings before his 14th place finish at the Circuit of The Americas in Austin on Sunday moved him to 34th place. He'll need to win a race and reach at least 30th in the standings to secure a spot in the playoffs.

Keselowski finished 14th at the Circuit of The Americas in Austin.

Keselowski finished 14th at the Circuit of The Americas in Austin. (Dylan Buell/Getty Images)

NASCAR has made it clear that unsanctioned changes to the standard parts on the new Next Gen Cup Series car, which was designed to control costs and improve competition, would not be tolerated.

"I’m pretty sure it scares the hell out everyone, which is probably some of the attention," Joey Logano said before the Texas race.

"NASCAR just said they’re gonna put the foot down. That’s like I was saying earlier, we don’t know what it was and what happened, but we do know the penalty was huge. So, I don’t know, but we know you probably shouldn’t screw around."

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Spire Motorsports owner Jeff Dickerson told the Associated Press that he's warned his staff that if any of them are caught cheating, they'll be fired.

"This new car is our gamble, this was the mortgage, and we told our team on Day 1 that we will not be the example. So we want to know what was done on that car because we will not be caught in the same position."