Just spray WD-40 all over each bushing and have someone bounce the car up and down as you spray each one. Find out which it is when the noise goes away. Then just simply spray the crap out of it more and drive the car a few days to see if it returns. If it returns then you will need to get a greese gun if it has a zerk fitting- if no zerk fitting them you'll have to dismantle it and rub moly lube all over it.