Eight Melbourne players have been handed different jumper numbers ahead of the 2018 season, with six new Demons grabbing new numbers after joining the club in the off-season.
The jumper was recently made famous by star forward David Neitz, who played a club record 286 games in the number.
Fritsch will wear No. 31, Baker will don the No. 33 and Petty will wear No. 35, as all numbers between 1-40 have now been filled.
Harmes, who has worn No. 43 in his 44 games for Melbourne, will now wear the No. 4, after Jack Watts departed for Port Adelaide in October.
Maynard will now wear the No. 20, after making his debut in the 48 jumper in 2017.