Young Ed, I think you just figured it out. If it were a very late '49 B1, but with some features of a '50 B2, that would explain the 'X', and it would explain why the serial number lookup thinks it's a B2 but the tag says it's a B1. And, looking on the pdf I have linked above, I could find a valid serial number range in 1950 for a B2 (I never looked there earlier since the badge says B1). So, with the Dodge branding with a valid serial number range, it's not a Desoto...I'm not going to worry about the fact that the serial number also fits into that Desoto's serial number range.
Thanks!!! I appreciate this. Anything else that can be gleaned from the tag or the firewall tag, I'd love to learn more.
Thanks!
Mike