On Friday, Cameron Campbell decided to vacate his seat in the #24 McLaren Artura GT4 that he was to share with Jake Santalucia and Anthony Levitt.
Campbell, however, has elected to focus on his Ferrari Challenge commitments.
Buchan is a two-time TCR Australia winner and last year competed in several GT4 Australia races last year.
Stewards confirmed they ratified the decision to allow Buchan to compete.
“Driver of Car 24 Cameron Campbell has withdrawn for the Bathurst 12 Hour,” the stewards report read.
“Stewards received a request from Method Motorsport for Joshua Buchan to replace Cameron Campbell.”
The team did have to overcome a hurdle, given the supplementary regulations state “No change of Driver will be permitted after 1600hrs (AEDT) on Thursday 30th January 2025 unless exceptional circumstances, as determined by the Stewards warrant a change after that time.”
The report continued: “Stewards reviewed the request and granted permission for Joshua Buchan to compete in Car 24.
“Stewards determined that due to exceptional circumstance Joshua Buchan is permitted as the replacement driver in Car 24.”
Method Motorsport is co-owned by Chaz Mostert and Guy McEntyre.