Here is some information on the side window frames, you can see the book verbiage. It is correct that inside windshield frames never came from GM in chrome or SS for the AD’s, it would be safe to assume it was for glare. The Salesman Data Books give details on them as shown, I have included 1949 and 1954 as examples (I have every book but 53, let me know if you would like another). This was an R.P.O not an accessory, meaning these were fitted on the production line as part of the package described. Corner windows were available separately on all cab models without the deluxe group (also an R.P.O., Regular Production Option).
1949 reference:
https://www.flickr.com/photos/advance-design_parts_co/49116468107/in/album-72157631872034068/
1954 reference:
https://www.flickr.com/photos/advance-design_parts_co/49116468327/in/album-72157631872034068/
This 1950 Salesman Order Book shows the Deluxe Cab would have cost you $51.90!
https://www.flickr.com/photos/advance-design_parts_co/8335509814/in/album-72157631872034068/

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