NASCAR confirmed to NBC Sports on Thursday that it is finalizing details of the 2019 Cup rules package, which is expected to be announced next week.

The rules package will have elements of what was run in the All-Star Race in May, but restrictor plates will not be a part of the package.

Instead, tapered spacers will be used to regulate horsepower. NASCAR also will legislate the use of aero ducts. About half of the races are expected to use this type of package.

The package goes away from the low downforce approach the sport has headed in recent years.

“To me it was more what the drivers and the crew chiefs thought about it,” car owner Tony Stewart told SiriusXM NASCAR Radio on Thursday. “Ultimately, from the owner’s standpoint what does it cost to do that. There’s much more to it than what the fans realize as far as doing a package like that. Now, you’re developing a motor for that package. All three manufacturers have to worry about development costs for motors. The cars have different things you have to do to them, which that is not the huge expense. The motor side of it is the biggest piece.:”

NASCAR and teams tried a new aero package at the All-Star Race that featured aero ducts to push air from the front of the car through the wheel well to create a bigger wake behind it, a 6-inch high spoiler, and a 2014-style splitter that was done to balance the front of the car with the changes made to the rear spoiler.

“I thought the race looked decent from my perspective,’’ Denny Hamlin said after the All-Star Race. “Maybe it could use some refinement but overall if the fans or the stakeholders believe they saw a good race, then we can work on it from here. I’m not really opposed to anything, really.’’

Car owners Richard Childress and Roger Penske both said in May that they’d be willing to try the package used in the All-Star Race in other races this season. NASCAR decided not to add the package for any other races this season in Cup.