The run channel is installed basically like the videos you see. Here is a pic of a 40 door with run
channel still in it. As you know there are guide channels and "clips" to hold it generally to door....and I assume, since 47 and up is also glued in, that yours will need glue also (3M weatherstrip adhesive, The run channel that Classic Truck sells for 1940 says use glue). If the whole inside door panel comes off, like it looks like it does, this will be real easy to figure out and install. Anyway study the Ebay pics for internal details of your door.
pic Albeit a panel truck door, probably same run channel design.
As soon as you get to the Ebay listing, click the pic, which will enlarge it/them. Then right mouse to "save picture as" to your computer.
47 install for refBend the channel VERY gently, a little at a time, so as not to kink the corrugation.
tclederman will no doubt notice that the tech guy says "fifty five and a half first series GM truck"

(inside joke)