Sonic Boooom---91 300ce

[e320 coupe]

Hi,

Im always in need of some good advice. When my car was running, I would here a loud boom toward the rear of the car whenever my car shifted gears. Mostly this occured when I was letting off the accelerator and letting the car shift into gear.

So, what do you guys think it is and how can I fix it?

thanks
a.e.b.