This thread comes up every now and then. I only have experience with the 88 cars, so I can't comment on the others.
The noise is coming from the sliders. They need to be cleaned and lubed. I've tried them all, and believe it or not, the best results are with simple silicone vacuum grease (also called stop-**** grease). This is the stuff that looks like Petroleum Jelly - milky clear color. Some auto parts stores carry it, but you have to look carefully, or find someone who knows something. All the "high pressure" and "high temperature" greases I've used have all hardened and the noise came back.
I really don't think it's the sliders themselves. I think it's the rubber boot chattering on the sliders. If you take it apart, you will see that the boot forms an o-ring seal on the slider. I think that it sticks, then moves, then sticks again, causing this noise. If you are going to work on these things, you can do us all a favor and perform a simple experiment.
Remove the calipers and pull the sliders out. Reassemble the silders WITHOUT the boots. Bolt them on the car and go for a ride to see if the noise is gone. Then, put them back together (don't want to travel far without protection) and see if the noise comes back. If it does, then you have found the problem. And if this is the real problem, then "putting in more grease" isn't the answer. We might have to look into a different material, or teflon coating or something like that.
Good luck,
-L
http://www.webelectricmagazine.com