well, these were the original (yes, OEM) pads that I removed. They
laster 60k miles, and may have lasted another 5k but I didn't want to
push it and be forced to change them in the middle of the winter. I
figure out I should change the pads now, make sure the brakes are OK
before the snow comes (yes, it's 3 month away, but why wait?).

So, I found a shim on the back of the outer pads, no shim at all on the
inner pads. If I were to install all the shims, they wouldn't fit!

and no squeals yet.