My 89 convertible makes a clunking/thunking noise from around the front end/sway bar especially when turning into a slight incline, like a driveway. I've replaced the sway bar bushings, end links and steering rack bushings to date, but the thunk remains. I have also replaced the very worn stock springs and struts with Eibach springs and KYB struts. I figure the remaining bushings are at least contributing to the problem, but I do not want to replace them with the stock (perishable) units. Does anybody make urethane replacements for the remaining bushings and does anybody have any thoughts on the source of the thunk?