You might be able to do it with the vent window frame in the door but it would be a PITA. You need to remove the vent window from its frame. I've only done it with the frame out of the door. To remove the frame, you have to remove the door panel, then remove the window regulator- there are several screws holding it in, which will be obvious when you try to take it out. Let the glass drop all the way into the door, then remove the screws holding the vent window frame into the door, including several small sheet metal screws going into the door from the front edge. At this point you should be able to lift the vent window frame out of the door. Next, remove window from the frame by unscrewing the nut & spring at the bottom of the vent window and the screws holding the window hinge to the frame. Now you can pull the old rubber out and replace it. If you are going to replace the felt in the channel of the frame for the main glass, now is the time to do it- likewise if you want to paint the frame, do it now. You need to drill out the old rivets. Replacement felt will come with new brass rivets. You can set them with a center punch. I used a little dishwashing liquid on the rubber to help get it into the frame. Reassembly is the reverse of disassembly. It's been over a year since I did mine so I may have forgotten a few details but hopefully that helps a bit.<br><br>A lot of work, but I sure don't miss all the wind whistling in on cold mornings.