I have a 97 XJ 4.0. It makes a low grinding or rubbing noise as I accelerate from a complete stop. It does not happen every time, but it does happen more often and gets worse when I pull a jeep trailer. I've been pulling the trailer a lot for the last two days. Today it seems to have gotten worse and is now shaking and vibrating as if the transmission is trying to turn. It could be described as a shutter. I've checked the transmission mount and it looks good. The U-joints seem good but I'll check them again. I just had a front U-joint go bad a few weeks ago and I changed out both. But, this does not seem to be related since it happened before and after.