I found my 63 vent windows I did not sell them - I sold the stainless off them and the mounting hardware for the vent assemblies.
To remove the vent window rubber, you have to remove the vertical track that the door glass rolls up in.
There is one philips screw at the top (in the vent window stop rubber -it comes off ). Then you have to drill out all the rivets holding the vertical track to the chrome frame around the vent glass frame. There are a pair of two of them and at least 2 or 3 single rivets spaced out to the bottom of the track. These rivets will be replaced by flat head zinc plated screws lock washers and nuts.
After the vertical track is removed -In picture number # 4 the two large philips screws they hold the vent window rubber to the pot metal chrome frame. The rubber is held to the angled part of the outside frame by 3 push in clips attached to the rubber inside the groove in the outside frame.
The bottom of the vent window rubber(horizontial section) above the vent controls is inserted into a C shaped slot in the frame .
pry both out with a long screw driver saving the 3 sharp edged clips attached to the vent rubber strips , remember how the rubber is installed -it goes back in the same location matching the top edge of the rubber with the chrome frame.
vent rubber for 63 and 64
https://www.steelerubber.com/vent-window-kit-90-0429-90
not sure this is correct - I can't remember if 63 and 64s had chrome beaded vertical tracks for the door glass to roll up along the vent windows
https://www.lategreatchevy.com/full...frame-vertical-window-channels-1963-1964.html
There are chrome stainless strips on the top of the vertical channels can be removed and polished on a buffer (4 stainless pieces) and reinstalled after polishing on a buffer.
the pictures below attached are for 62 impala HT and convertible but the items i mention above still apply.
the rivets have been removed and part of them replaced with screws and nuts (the screws and nuts in a group used are one of the pictures) + some of the screws and nuts are installed on the chrome beaded fuzzy track(picture # 3 and # 5.
note the special clips in the first two pictures. Some guys have not salvaged these clips and glued the vent weather strip in the slot.
I save the clips and install them on the new weatherstrip -a very very difficult process without breaking the 4 bendable tabs -the clip on the table has 2 missing tabs on it.
Paul