Kip, while I thought that for a long time too, i noticed recently that while trucks in these years only had one lock on the passenger side, GM cars (46 and up at least) had locks on both sides. I'm not sure why cars would be different.

1946 GMC Pickup - S-10 Frame, 455 Buick, TH400, original patina.

My 46 GMC on Photobucket