1999 323i knocking in rear

I have recently developed what sounds like a knocking in the rear end of my car. The knocking starts at slow speeds and seems to speed up when i do. It feels like a dull wood knocking type sound. The sound is coming from what sounds like the center/right rear. The car is a 1999 323i sedan with 5spd manual and 190000kms. Any help would be appreciated.