Customer teams are unlikely to be able to buy brake ducts from other outfits from next year after an agreement to change Formula 1's listed parts rules for 2020.
Smaller outfits like Haas and Alfa Romeo have benefited from forming customer alliances with Ferrari, with Haas buying as many parts as it can from its supplier.
But the success of that business model has caused concern among more traditional outfits like McLaren and Williams, which elect to produce as much of their cars as they can themselves.
The car parts that teams must make themselves are labelled in the rules as 'listed parts', and are currently limited to the survival cell, the front impact structure, the roll structures and bodywork with the exception of airboxes, engine exhausts and any prescribed bodywork geometries.
Ahead of F1's major revamp for 2021, some outfits have pushed for rules tweaks that force teams to make more of the car themselves, while others are eager to keep the customer car route open.
The matter was discussed in last week's F1 Strategy Group and F1 Commission meetings, as the championship moves towards a model that balances out an increase in standard parts with the requirement for teams to do more of the car themselves.
One of the key battlegrounds was related to suspension, and there had been calls for it to be added to the listed parts rules - something that would force a team like Haas to invest heavily in new design facilities.
But it is understood that a compromise is now likely on this front, with the basic suspension set-up still purchasable, but the aerodynamic elements around it needing to be designed by each team.
However, one change that looks set to take place as early as next year is a plan to make the brake duct a listed part for 2020.
Sources claim that the move has drawn majority support from the F1 Commission, which is made up of teams and other stakeholders, and will now be put forward for ratification by the FIA's World Motor Sport Council.
Although brake ducts are a relatively small part of the car, they have often been utilised by teams for aerodynamic benefits - chiefly for managing airflow and adding downforce.
The move to add brake ducts to listed parts for 2020 will add workload and expense to a team like Haas that purchases its ones from Ferrari.
It also closes the door for other teams that may have pondered sharing the parts longer term.