I got a set from a bolter from the "Parts wanted Section" of this forum
as stated above try posting there.

for new try
Rhode Island Wiring they carry GM metal light sockets
On the left side of web site click on
"supplies"
then look under
"Junction Blocks, Fuses, Seal Beam and Instrument Light Sockets"

also
http://www.americanclassic.com/Google_Base_HTML_Pages/LG844-1949.htm
Dont forget the socket for the ignition
Good Luck

DADS50
YouTube
1950 chevy 3100