Pedzisa mutsara unotevera: Brock akatyairawo Holden Monaro 427C yeGarry Rogers Motorsport (GRM), achikunda mana kubva kumakwikwi mana mune izvo zvaifungidzirwa kuva imwe chete pakuonekwa mumakwikwi ekutsigira kwe
2003 Australian Grand Prix muMelbourne. Izvi zvakamutungamira kutyaira 2nd Monaro yakavakwa uye inomhanya neGRM muAustralia Nations Cup Championship, GT-mhando yemakwikwi emota dzakagadziridzwa zvakanyanya uye dzekunze mumugwagwa muna 2003 asati amisa timu yake yega iye nemwanakomana wake James muna 2004 (naMonaros yakapihwa neGRM). Akawana gumi Bathurst kutsungirira kukunda muna 2003 paBathurst 24 Hour, paakakunda, naGreg Murphy, Jason Bright naTodd Kelly muGRM Monaro yake, zvine nharo inofambiswa ne7.0L 427 cui V8 injini pane 5.7L Gen III yakashandiswa nekugadzirwa kweMonaro CV8 (nharo yakabva kune imwe motokari muNations Cup ichikwanisa kumhanya injini yakasiyana nehukuru kubva pane chigadzirwa chekugadzira icho chaive chakavakirwa. Mutambi weTriple Nations Cup Jim Richards akatumidza Monaro se "Better V8 Supercar" apo yakatanga kuonekwa pa2002 Bathurst 24 Hour).