How is the pad that mounts below the windshield held on for the roof rail weatherstrip? I thought there should be some plastic plug or something but nothing in the bag.

What year and model?

70 2dr hardtop.

I'm not following your question. The windshield and roofrail are different areas. The roofrail weatherstrip is above the side windows and is held on by the roof rail channel which bolts to the underside of the outer roof.

Here's a pic that shows what looks like plastic buttons attaching the weatherstrip to the body.

http://www.chevelles.com/showroom/data/500/roof_rail_ws.jpg

Yes, the push pads hold that end of the weatherstripping in place.

Got it figured out, the plastic buttons were missing from my package. Thanks for the help.