have you checked the struts and springs? they could be bad or going bad and that load may have put just enough strain on it to make it worse. id check that to start. mine clunks in the back but i think mine is a blown strut.
00 Toreador Red SVT-#1751 of 2150
KKM intake
No resonator
Eibach springs 2 1/2" drop
No door ding guards
Side markers