For some reason, when I'm reversing, the car has a knocking sound. It's does it when I'm reversing slowly. The sound seems like its coming from the front. I don't think it's the balljoints because it happens when i'm reversing. When I move forward, It's fine. Plus, I just had the balljoints done. Waht can it be? thanx

 

I'm in the EXACT same boat. I'll crawl under and tell you what I find.

 

If I had to guess, which I do, it's your caster bushing. There are a couple of threads discussing this. Try "caster bushing daizen" in advanced search and you should find more information than you ever needed.