I understand it is a 49 with a 54 motor in it. If it has an open drive then both the trans and differential are not original. You could have the original rear axle but with an open drive the third member could be from a bit later truck. All 49 half tons had closed (torque tube) drive.
Bill


1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice