Lots of things can cause this. I would suggest that you review the entire front suspension playing particular attention to ball joints (although this normally felt in steering first)
Also, check lower control arm mounts - look for wasted bushing and - cracks where it attaches to the cross member. (I had a crack on my '75).
If it is cracked, don't just try some yahoo weld it. The crack needs to be etched and then welded. I would recommend bracing the mount as well. On the passenger side its right next to the fuel pump so take precautions.
Friday, September 11th, 2009 AT 4:46 PM