• Base Chakra: Laum, vibrated as LLAHHH – UUU – MMM*
• Sacral Chakra: Vaum, vibrated as VAHHH – UUU – MMM
• Solar Plexus '666' Chakra: Raum, vibrated as RAHHH – UUU – MMM**
• Heart Chakra: Yaum, vibrated as YYAHHH – UUU – MMM
• Throat Chakra: Haum, vibrated as HAHHH – UUU – MMM
• Sixth Chakra: Aum, vibrated as AHHH – UUU – MMM
• Seventh Chakra: Maum, vibrated as MMAHHH – UUU – MMM
In another thread (https://ancient-forums.com/viewtopic.php?p=74921), it was said that the Heart Chakra (4th) is AUM on its own without a preceeding letter, because it is the neutral/connecting Chakra, and the 6th Chakra (6th) is YAUM, because this which you quoted is outdated information which has yet to be updated and corrected.
Of course, AUM could work in any/all Chakras, as it is in all of the Mantras + a preceeding letter, and the Solar Chakra (gold/yellow, AU gold atomic number 79) is the powerhouse of the Soul, the most important Chakra in at least one sense, but each AUM word is more specific and powerful corresponding to each respective Chakra.