The Book says to install new ones and not to reuse them. Those are likely the ones that end up in the sludge receptacle. I have found them there myself a few times. One time I found one, but there weren't any missing on the connecting rods. Goober must not have clean out the oil pan in 1954 when he peeled some shims during a half-hearted overhaul.
I don't use them on insert bearing engines even if that came with them, but I won't drive one that has a rod knock either.
