On my 96 Impala, I started hearing a clunking noise from the rear on left turns a couple weeks back. I guessed that it might be the differential starting to digest itself after a quarter million miles. Went to the trouble and mess of taking the cover off and it looks just like it did last year when I replaced the fluid - brand new. No teeth or debris in the bottom, no wear on the parts I could see. I figured, so that probably ain't it. While buttoning it back up, I looked over at the driver's side and noticed that the C channel part of the frame had broken off from where the frame starts to get serious again, a bit forward of the leaf spring mount. Didn't see any rust, looks like it just plain broke. Anyone else have this problem? I'll be taking it to a frame shop this week to get it fixed, wondering if there's any pitfalls to this problem I should know about.