Intro
My Jeep has been making a clunking noise when I would put torque on the drivetrain, especially when I took off in first gear and then again when I engaged second gear. It would also happen when I hit sharp bumps in the road. This clunk was very solid and sounded/felt like something heavy was hitting the frame. This made me suspect that my transmission or transfer case was twisting and hitting the skid plate when tourque was applied. Although it is very difficult to see anything that is above the skid plate, I could see the side of the tranny mount and it looked wore out. I assumed this was my problem and looked into a replacement.

Sellecting a replacement
My first stop was Quadratec because they have nice pictures. They sell one polyurethane model made by Daystar. I then did a little online searching and found out that there are several polyurethane models out there and that all of them will greatly increase the amount of vibrations from the drivetrain into the frame of the Jeep. It turns out that polyurethane is good stuff for certain applications but for engine and tranny mounts it may not be better than good old rubber. I found that the only rubber mount I could find was the oem model. Knowing that I am going keep doing extreme things with my Jeep, I decided that I can live with the extra vibration if the new mount is bombproof and helps keep the drivetrain stable. I did a little online searching for the Daystar mount and found that it was best ordered from a local 4WheelParts store. It cost me $48 shipped and took 2 days to get to me.

Installation
I enlisted the help of a friend and we went to work. First job was to take the weight off the transmission crossmember/skidplate. I tried the old jack on a 2x4 under the oil pan trick but there was just not enough leverage to lift the tranny and transfer case. So I jacked on the tranny itself placing a 2x4 between the jack and aluminum. With the weight removed from the skidplate, we unbolted it. The skidplate seems to weigh about 40-50 lbs. and is easily handled by two guys. Once removed, I got a good look at the old mount and this is when I found out that it was not in that bad of condition. It was worn but not like I suspected. We easily replaced the mount and were ready to reinstall the skid plate. I decided this was a good time to wash off the skidplate because it was full of rocks and dirt. During this process I found a medium sized rock that was stuck in some oil near the middle of the skidplate and it became apparent that this was the cause of the clunking noise. When the engine/tranny moved under torque, it was hitting this rock. Well we learn as we go and replacing the tranny mount was not a loss because I needed to tighten up the drivetrain anyhow for rock crawling. Reinstalling the skidplay was not overly difficult except for one problem. With all the dents and scrapes on the skidplate, it was bent slightly and this made it longer. Getting the large side bolts to line up was difficult but doable. In the end the job took us about an hour and that included lots of examination and sight seeing.

The old mount in fairly good condition.

The new Daystar polyurethane mount.

After thoughts
The new mount definitly tightened up the drivetrain and as I expected, it is not isolating nearly as much of the drivetrain vibrations as the stock rubber mount. This is only a problem when idling around town or during initial take off in first gear. The more I drive it, the less it bothers me and soon it will be just part of my Jeep. Knowing what I know now, would I do things the same way again? I think so.