Apologies in advance for the length of this:
I don't know if this is directly applicable to the early post '46's or not. If it is, hopefully this will help someone. I got into my passenger door because the glass frame separated from the horizontal bar the glass sets in. There are apparently some special fasteners for the connection between the two but mine are long gone. I'm going to try Chevs, Carter's, Bowtie Bits, etc. Found them for the 47+ trucks, don't know if the same will work on my '46.
Anyway, "while I was in there"
I thought I may as well clean up the door interior and put in new rubber, window channel, glass wiper rubber, etc. There is a tiny slot all along the bottom of the window opening on the door and a matching one in the door panel. The glass wiper rubber is "d" shaped and slides in using 50-50 mix of glycerin & water (I'm told, haven't done it yet). Over the decades these wipers start to chip off. My truck had the 64 year old originals! To say they were in there to stay is an understatement - hard as a rock. After struggling with a putty knife and hammer on one side I noticed my drywall hole saw.
Worked like a charm! Not exactly an "easy" job, but in comparison to the putty knife - a snap. These drywall tools are a $5-6 item at Home Cheapo. I keep one in my travel tool box because I have already used it to save a JetSki guy that sucked up his anchor rope into his impeller.
Near the end of this job I figured out if I flipped the saw over it is pointed and works great to get the small remnants out. Hope this helps someone else.
P.S, Pardon the photo quality. They're from my cell phone, all I had with me at the time.