"clunk" sound 300D

Yes, it's me again. I'm going on a long
trip tomorrow in my 81 300D and i've noticed
a few things I hope to get a little feedback before leaving.

When i put on brake and almost come to a stop, i can hear and feel a distinct "clunk"
sound under the car. I can't yet figure
exactly where it's coming from, but possibly toward the back. Any ideas? Everything along
the tranny looks fine to me underneath, but
then I'm not 'really' experienced in that
area.
Thanks