If the rear is knocking....

[shadrach74]

I get a light vibrato type knock over light bumps. Almost a rattle but low pitch in sound... Sway bar drop links? The car is going in for alignment on Thursday. I'm not getting any movement in the suspension when I poke and prod, and it does not make noise in the turns or over larger bumps,it's primarily over things light small speed bumps and pavement abnormalities.

I know that diagnosing suspension problems over the internet is sort of a silly request, but thought I'd ask if this is a typical mode of failure...

Thanks!