IIRC, you can buy class 8-10 positron shields from:
Malta, Omicron Alpha (Outcast)
Ruiz Base, Omicron Beta (Oucast)
and all the corsair planets (I haven't found them all yet and can't remember the names of the ones I found.)

class 8-9 Molecular shields from:
Freeport 9, Omicron Theta (Zoners)
Freeport 8(?), Omega-whatever that's on the other side of Omicron Gamma.

I don't think there's a class 8 graviton shield.

Hanlon's Razor: Never attribute to malice that which can be adaquately explained by stupidity.

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