The team has confirmed that Reynolds' engineer of the last two seasons, Nathaniel Osborne, will fill a new position of chief engineer across the four-car team.
Reynolds has been assigned recent recruit Brad Wischusen as his race engineer.
Winterbottom will meanwhile be working with his former data engineer Jason Gray, who replaces the now Red Bull man Grant McPherson.
“With Brad joining the team we thought it was time for a shake-up within the team to put a few sets of fresh eyes in different roles,” explained PRA team principal Tim Edwards.
“Having Nathaniel oversee the engineering group was an important move with the introduction of the FG X.
“I believe the new structure not only rewards the efforts of our existing engineers but will also provide us with fresh ideas to keep up our development and help us move in the right direction.”
Edwards has meanwhile confirmed to Speedcafe.com that Mostert will be given a fresh chassis for the new season.
Winterbottom will continue in the chassis he debuted last year, while Reynolds reverts to the car he raced for the majority of the 2014 campaign, prior to its big crash at Bathurst.
Heimgartner's car will be the former Jeld-Wen entry, which PRA has taken ownership of as part of the split with Charlie Schwerkolt.
The Mostert and Winterbottom cars are both scheduled to start the season in FG X form, with the remaining two to be upgraded early in the season.