You generally don't see the early headliner with the mid-49 door tracks. That being said as shown in my earlier post there appears to be a series of running changes illustrated by the dating on the headliner material (1947- Production start for 1950) if you want to use it you need the screw on bow for the rear headliner hold down and you need a screw on center bow. You will also need the 47-mid 49 cardboard that is made for this application, it has different punched cut outs for the screws. I would put forward the hypothesis that with the number of assembly plants an earlier cab configured like yours could have easily come through as they were used up.
https://www.flickr.com/photos/advance-design_parts_co/15744122484/in/set-72157631868452754

1950 Chevrolet 3/4-Ton 3600
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