To remove the slop and wiggle form the rear end during corners.
It is always cool to me to say I have changed something. I am definately not a stock loving person.
Since I am having trouble locating a reasonably priced 88 cradle I am looking to improve the 86 cradle. I had the cradle out of the car replacing the stock transmission mounts with custom mounts that I made. I noticed that the from rubber mounts were is terrible condition. I decided to replace them with some welded in washers. I burned out the rubber with a torch. I always love burning rubber :-). I then welded in two washers on each side of each front mount location on the cradle. I then welded the old bushing from the rubber mounts into the center hole of the washers. I of course measured so it would fit back in the car.
It was a real pain to get the cradle back in the car. When the rubber mounts aren't perfectly lined up you can force the bolt in and the rubber will flex letting the bolt go through. Not so with solid mounts. I had to pull this way and that way moving the whole cradle on the dolly a 1/4 inch this way, then an 1/8 inch the other way, then an 1/16 back,... It was hard. Once I got it in place both bolts slipped right in. I did a good job measuring.
When I first started the car I was shocked at the amount of vibration. The whole car vibrates like a Harley. I was a little worried I might have made a mistake. I pulled out of the driveway and when I went around the first corner I knew I had done the right thing. The car is much much more solid. I would rate this change right up there with addind the rear sway bar.