Both the trans and axle should have numbers on them. I don't recall if those numbers indicate when the units were built. If I remember long enough I'll look when I get home tonight.
Assuming those units have not been replaced a date code would only tell you the truck was made no earlier than that date.
Could your 1950 motor be what you need to call it a '50 or earlier?
I've seen people update the doors just to get wing windows. It could have been done to this truck too.
