Both of my side windows are really loose. That is, they wiggle side to side. It doesnt help that both my seals are shot. When I close the door, I can hear the glass hit the top of the door frame. I restored an 84 last year that had the same problem, but that fix was easy. There were felt lined window guides that I replaced that did the trick. I don't see such a part for my 79. So my question is, what serves the same purpose on C3s? Is it just the seals that hold the window in place and from moving side to side, or something else?

Once again, thanks for your advice!

Maybe this might help... http://www.corvettemagazine.com/component/content/article/39-body/44-the-outside-seal.html

That covers the outside seal pretty well. The thing I did first was to pull the glass and all the mechanism out, rebuild all that stuff, and then do the outside seals etc. I figured I didn't want to have to do it twice. Be VERY careful and take your time adjusting the glass. OH...and if your car needs new weather strip, do that before the glass. MikeMc712009-03-11 08:26:58

I was able to mostly solve that problem with new door glass anti-rattle cushions. It's an easy fix for a novice like me. There is still a small rattle in my driver's door but I can live with it for now.

What they said above.  If you have an Assembly Instruction Manual (AIM) for your car there should be step-by-step directions in it for adjusting the windows.