According to this http://www.oldgmctrucks.com/page0015.html you have a 1949 that falls near mid-year (13,531 FC-152 models produced). Nobody but the factory is going to spot weld that bracket where it is (TBC). I have no idea why you do not have the channels or weatherstrip assemblies other than a lot can happen in 71 years.
One way to confirm earlier weatherstrip is to look for these holes on both sides of the dash for screw removal.
https://www.flickr.com/photos/advance-design_parts_co/49456568082/in/album-72157631868452754/

1950 Chevrolet 3/4-Ton 3600
More pictures on Flickr