GRM built two Monaro back in the early 2000s to compete in the Nations Cup series, as well as tackle the short-lived 24-hour race at Bathurst.
The Holdens proved unstoppable at Mount Panorama, winning both the 2002 race with Garth Tander, Steve Richards, Nathan Pretty and Cam McConville, and the 2003 race with Peter Brock, Greg Murphy, Jason Bright and Todd Kelly.
GRM retained ownership of the 2002 winner, that car set to be reunited with the circuit as part of the Holden Bathurst Revival during this November's Bathurst International.
The team has also used the coronavirus break to build what is technically a brand new Monaro out of a spare shell that was stored in a shipping container.
With the Holden brand being axed by General Motors as of the end of the year, and production of Holden cars now entirely overseas, GRM expects the car to be the final genuine Holden every built.
“When COVID-19 first hit, we were looking for some work to keep our guys busy, and there were containers out the back with quite a bit of stuff for the Monaro in there, including a body shell,” said team boss Barry Rogers.
“With Holden leaving Australia, we felt this was a great way to say thanks and farewell, and it will most likely be the last Holden ever built in Australia. For our team, we feel that is quite special.
“The Bathurst International event is going to the perfect way for GRM to salute Holden and the recognise the massive role it has played in Australian motorsport and our team.
“The new car is built to the exact same specification as the original car.
“Ron Harrop had quite a bit to do with the original, and he is building uprights and a bunch of other bits for it. He is semi-retired now and works in his own shed in country Victoria. He has sourced and retained all of the IP to produce those components.
“[Jeff "Gypsy" Marshall] is currently rebuilding the 427 engine that we proudly displayed in our boardroom. Thankfully we retained that engine after all of these years.
“We can’t wait to get both of them to Bathurst and get them around the track.”
The Bathurst International will take place on November 12-15.