I believe for the AD's the floor brake used a sponge seal as did the floor shifter, the rubber boots came later? I don't believe either one was actually a factory item. It appears from the following the starter bellows was.
https://www.flickr.com/photos/advance-design_parts_co/12315091125/in/set-72157640522200463
https://www.flickr.com/photos/advance-design_parts_co/11973900943/in/set-72157639819091033
https://www.flickr.com/photos/advance-design_parts_co/15724927397/in/set-72157649468726416