Chrysler automatic xmissions have been known to 'clatter' as they are placed into gear. The design of the xmission will quickly open/close the hydrolic valves in the xmission-case. Each open/close of a valve makes a 'click'. You can imagine that if they all do it in succession, it will be a series of clicks ..... or a breif clatter sound.
I have heard this 'clatter' sound on Chrysler xmissions going back to the 1980s.
BEWARE: This is one reason that you MUST MUST MUST use only the proper Chrysler-reccommended Automatic Transmission Fluid in a Chrysler xmission. Using "universal" or "Dexron" will cause the valves to fail.