Motorsport.com understands the squad has agreed to a two-year deal with telco giant Optus to continue backing Mostert's car.
Optus joined WAU as the major backer of Mostert's car at the beginning of this season, sharing the naming rights billing with long-time WAU partner Mobil 1.
The new deal means Optus will follow Mostert and WAU across the GM/Ford divide, with Mostert racing an Optus Mustang for the first two seasons of the Gen3 era.
WAU isn't just facing a move to a new-generation car next season, but also calling time on its long, storied association with GM.
The former factory Holden team, which made the Holden Racing Team brand one of the most iconic in Australian sport, announced a sensational defection for Ford earlier this year.
WAU will be part of a five-team factory-supported Ford effort that will span across 11 Mustangs on the grid.
There is speculation that the team will celebrate the end of the GM/Holden era with a special livery across both the Mostert and Nick Percat cars at the 2022 season-ending Adelaide 500 in four weeks time.
