How to fix a clunking rear diff bushing on an Infiniti FX50

Unlike the FX35/FX37, there is no replacement bushing for the rear differential on the Infiniti FX50. Your options are to either replace the entire rear subframe ($$$) or to fill the bushing with some polyurethane. I used some 3M Window-Weld 08609 (~$35), and it seems to have reduced the clunking by 80 to 90%. Good enough for me!