MSR announced today that experienced race engineer McDougall has left the two-car squad, as well as confirming that he's headed to Triple Eight for the coming season.
That follows news that Bathurst 1000-winning race engineer Grant McPherson has parted ways with Triple Eight and will take up the Head of Performance role at Walkinshaw Andretti United after serving six months of gardening leave.
Should it be a straight swap, McDougall would take over from McPherson as Shane van Gisbergen's race engineer.
Triple Eight is yet to publicly confirm McDougall's appointment or announce its engineering line-up for 2021.
MSR, meanwhile, says it will look to promote from within to replace McDougall, but hasn't ruled out an external hire either.
"This move comes at a time when MSR [is] in the process of a performance restructure in both [its] mechanical and engineering departments ahead of the 2021 season," read the media statement from the team.
"This change in team personnel offers further opportunities for all staff, present and future, plus the team as a whole to improve their efforts in 2021.
"Matt Stone Racing [aims] to continue to enhance [its] succession plan within the engineering department as the team look to promote from within, while also looking for, and in discussions with, other possible candidates to join the team.
"Matt Stone Racing [is] certain this move will further strengthen [the] already-established engineering and technical relationship and alliance with Triple Eight moving forward.
"We thank Wes for his dedication to Matt Stone Racing and wish him well on his new endeavours."
McDougall joined MSR back in 2016, helping Todd Hazelwood to the Super2 title the following year before the squad stepped up to the main game.
He had previously spent more than a decade working for Stone Brothers Racing/Erebus Motorsport.