Question about CPU upgraded parts

[Emerald Emblem]

So I was just playing in a dungeon on Lowee grinding money, when I stumbled upon one of the upgraded proccessing unit parts for Blanc, now this prompted a new dungeon appearing of which I found another part, another dungeon opened up at level 99 difficulty of which i managed to attain the part from there but unable to beat the boss.

The question I have is that since there are 3 more of these parts to get for Blanc, the dungeon level is 99 that I need to beat, will other level 99 dungeons be unlocked to get the 3 remaining parts, or are they gotten elsewhere like a rare drop from the bosses in the dungeons you can get the units?