99 T/C strut noise

I am experiencing an annoying noise from the front struts when passing over bumps. I do not believe that the front end is bottoming, but it seems to give a deep thud sound. It is not a tin sound, but more like something loose and insulated. What is a jounce bushing? Are these something in the strut assembly and susceptible to getting loose? I have read about the springs could be the culprit, but could it be that the front spring is bottoming and the strut is hitting a bottoming rubber ? Jounce bushing? Thanks for some help.

Wow, nearly a year later and I found the noise. It turns out that the left sway bar link joint was worn in its socket. Replaced this and noise is gone.
chuck's

Yup, sway bar links and bushings cause the majority of suspension noises on these vans. Thanks for coming back with the fix.