If you have an FTP program (like CuteFTP), go to ftp.aladdinsys.com. Then browse to: /pub/_old/mac/StuffIt_Expander/
StuffIt Expander v6.0 direct links
StuffIt Expander v6.01 direct links
Alternative download locations:
ftp://members.aol.com/aladdin/pub/
ftp://ftp.scruz.net/users/aladdin/public/
Aladdin Systems website: www.aladdinsys.com