300D Suspension Problems.. help!

Hey all,

I just started up my 1992 300D 2.5 and I drove it, planning on going home from school (I live on campus) and it felt like my car wasn't "bouncing" as much. I thought one of my tires might be flat, so I got out and checked, but it turned out that the left rear section of the car doesn't bounce at all. It's like someone has just taken the shock totally out of the car. What does this sound like to you? I think it might be the suspension depressurized, but I'm not sure, I'm not good with this kind of thing. Any help?