mitfan311

I just got a 95 4runner. Its 4wd. I have noticed a rattle or clanking from the front driver side wheel that varies in frequency depending on speed. So I jacked up the front and spun the wheel. There was definitely something clanking as i turned the wheel. I noticed that when I spun it in reverse the drive shaft would rotate with it and there was no noise. Only when i spun it forward is when is rattled and the drive shaft did not turn. So I put it in 4wd and there was no noise. I cant drive around in 4 wheel all the time. What is wrong or what needs to be replaced? What I should do if anything?
Thanks