What do I need to do to eliminate the rattle from my windows?

My guess, the vent window channel weatherstrip is bad. Its located on the front edge of the glass and rides up and down in the vent window channel. They are usually wore out or deteriorated completely which leads to bad window rattle.

Actually all weather stripping is new. Any other thoughts? Is there a page in the 70 service manual that would cover this? I don't have one but thinking of getting one.

Could be a part inside the door that the glass rides up on worn or loose? Behind the arm rest area in some cars are metal "arms" of some sort that have a cloth, felt, etc. material to rub against the window and keep it firm. Sorry for not using the technical terms.

Do they rattle all the time or just when down? Can you physically move the glass? I would guess something else is moving as b-bodies slide inside a track front in back where e-bodies for example the rear has a part that slide in the track attached to the glass. I would check the rods for the inside door handle and lock.

Yes they rattle when they are all the way down. 1/2 way up or all the way up they are fine. I'll pull the panel and try to see what's going on.

take the panel off.tap on the door frame with a rubber mallet or your palm while you reach up inside the door and push on things, when you can stop the rattle your close to finding its source.

At the bottom of the vent frame a bracket is riveted on, quite often breaks off due to closing door by window frame.