Erebus and Grove had finished first and second in each of the two Thursday practice sessions at Mount Panorama but it was the latter which took bragging rights on Friday morning.
Payne set a late 2:05.2855s in the #19 Penrite Mustang and Reynolds set an even later 2:05.3738s in the #26 Penrite Mustang, beating Kostecki's early 2:05.4377s in the #99 Coca-Cola Camaro.
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Kostecki was in fact the only Chevrolet driver in the top five, which was rounded out by Dick Johnson Racing team-mates Will Davison (#17 Shell V-Power Mustang) and Anton De Pasquale (#11 Shell V-Power Mustang).
Cameron Hill (#35 Truck Assist Camaro) took sixth, from Broc Feeney (#88 Red Bull Ampol Camaro), Chaz Mostert (#25 Mobil 1 Optus Mustang), Cam Waters (#6 Tickford Racing Mustang), and Andre Heimgartner (#8 R&J Batteries Camaro).
Being the first refuelling session of the event, teams also took the opportunity in Practice 3 to rehearse pit stops, including brake changes, with varying levels of success.
A mixture of primary drivers and co-drivers had started the hour-long session but it was a couple of familiar names who made an early impact.
Two-time Great Race winner Mostert was several tenths up on the field when he wheeled the #25 Walkinshaw Andretti United entry to a 2:06.4228s on his first lap, giving the wall the lightest touch on the exit of Forrest's Elbow.
However, after Brodie Kostecki's co-driver, David Russell, had set the fastest lap time of Thursday, the championship leader himself blazed to an even quicker 2:05.5774s straight out of the box in the #99 Camaro.
Notably, after Tickford team-mates Waters and James Courtney were dispatched with new tyres, the former gave the latter a tow down Conrod Straight in a sign of possible qualifying tactics.
Waters was third on a 2:06.0214s and Courtney (#5 Mustang) moved up to fourth with a tow-assisted 2:06.2968s while, meanwhile, Kostecki had improved slightly to a 2:05.4377s.
De Pasquale had not long moved up to fifth before he improved further to a 2:05.6235s which put the #11 DJR entry into second place on the timing screen.
Similarly, Feeney went fifth and then third with a 2:05.6507s on the latter of those two laps in the #88 Triple Eight Race Engineering car.
The car was thus showing no obvious ill effects after co-driver Jamie Whincup had an off at The Chase and also touched the wall on drivers' left at The Cutting during an earlier run.
A red flag was called in the 43rd minute when Zak Best stopped on the side of Conrod Straight after the #5 Mustang went into some sort of limp mode having broken a belt.
Kostecki still led at the time from De Pasquale and Feeney, but Russell advised that the former was switching focus to race running.
Mostert was fourth, from Waters, Reynolds, James Golding (#31 Nulon Camaro), Courtney, Will Brown (#9 Coca-Cola Camaro), and Heimgartner.
After a halt of almost five minutes, pit exit opened again.
Shane van Gisbergen (#97 Red Bull Ampol Camaro) had a twitch through McPhillamy Park as he rounded the #98 Shell V-Power Mustang to his left, then an off at The Chase.
His team-mate Zane Goddard, in Triple Eight's wildcard entry, had the wildest moment of all through McPhillamy when the #888 Supercheap Auto Camaro broke loose off the crest and ran through the gravel trap, but he was able to stay off the walls.
As all of that was going on, Hill went third on a 2:05.6281s in the #35 Matt Stone Racing Camaro before handing over to co-driver Jaylyn Robotham for the final minutes.
Cloud started to cover Mount Panorama for said final minutes, creating an opportunity for those on qualifying sims.
Payne jumped from seventh to the very top with the 2:05.2855s in the #19 Mustang, before Will Davison clocked a 2:05.4992s and then Reynolds, the 2:05.3738s.
Brown/Jack Perkins were classified 16th, van Gisbergen/Richie Stanaway in 19th, and Craig Lowndes/Goddard in 23rd.
Practice 4, another all-in session, starts at 13:05 local time/AEDT.