[Rwillia4]

The cause for break squeal is harmonics between the brake caliper and the pad. It is like rubbing your finger around the rim of a crystal glass, the sound you hear is the resonating frequency. To stop it you need to have something between these surfaces. I would guess you have nothing. I agree the “break quiet” works well. When installing, clean the back of the pad with acetone or it will cook of in short period of time.
Another fix is to get some thin steel sheet trim it smaller then the size of the pad but bigger then the caliper psiton diameter, and so it is supported buy the pad guides or bent around the pad (not interfering with the pad material). This piece should not be symmetric and the greater it is not symmetric the better it will work. It will take some time to get the template right but silent bliss will be in your future (or the rumble of a 351!)