Since it relocated from Phillip Island to Bathurst in 1963, the Great Race has traditionally been an October affair.
The 2021 Repco Bathurst 1000 will be the first Great Race to be staged in December as part of a six-day festival of motorsport.
The Great Race has been staged in Bathurst in October 51 times, and it was held in November between 1998 and 2000.
However, the race has also been held in September four times - and each time, on September 30.
The race was traditionally run on the Labour Day long weekend in New South Wales in early October.
Brock and Richards crushed the opposition in 1979
Labour Day on the Monday in 1973, 1979, 1984 and 1990 was October 1. All four years saw Mount Panorama stage four historic races on September 30.
The 1973 race was the first Great Race to be held under the new metricised distance of 1000 kilometres.
Allan Moffat claimed his third win in the event, having won the race under its previous guise of 500 miles in 1970 and 1971.
The 1973 race was also the first and only Bathurst win for five-time Australian Touring Car Champion Ian Geoghegan.
John Goss claimed pole and led the Falcons of Moffat, John French and Fred Gibson ahead of Peter Brock.
Perkins and Brock celebrate in 1984
Gibson and French fell out of contention, with Goss leading Moffat, who would survive a spin at Griffin's Bend.
Geoghegan made up the difference to Brock's co-driver Doug Chivas and claimed the lead on lap 78.
A collision for Goss dropped him out of contention, with Geoghegan handing the car back to Moffat.
Chivas led Moffat, but the Torana ran out of fuel, coasted back to pit lane, and Chivas famously climbed and pushed the car up the hill.
Brock had his redemption six years later when he combined with Jim Richards to win the 1979 race by a staggering six laps.
Grice and Percy celebrate their 1990 win
Brock and Richards won their second successive Great Race, with the Holden Dealer Team Torana never headed from pole position.
The duo easily beat the previous winning margin of two laps set in 1975.
Such was their dominance, that Brock claimed the lap record on the final lap of the race.
The third September Great Race, in 1984, would be the eighth of Brock's record nine Bathurst wins.
Brock combined with Larry Perkins in the iconic day-glo Marlboro Commodore VK for HDT.
It was the third consecutive victory for Brock, Perkins and the HDT which, with John Harvey and David Parsons second, scored. famous one-two form finish.
Happy days for British driver Percy in 1990
The 1984 race is affectionately known as 'The Last of the Big Bangers' in reference to the Group C touring cars, which were competing at Mount Panorama for the final time.
The fourth and final Great Race to be staged in September was arguably the biggest Bathurst upset of the 1990s - and it came in the first year of the decade.
The Holden Racing Team, with veterans Allan Grice and Win Percy behind the wheel, defied Sierras and Nissan's all-conquering GT-R to claim victory.
Sierras had won in 1988 and 1989, but fell by the wayside in 1990 as Grice went on the claim his second win, and Briton Percy's first.
Paul Radisich and Jeff Allam spared Ford's blushes with second for Dick Johnson Racing, with Perkins and Tomas Mezera third despite an ill-time Safety Car late on.