What size 1949 GMC?
Many GMC 1/2-1 ton truck parts match up with Chevrolet 1/2-1 ton trucks.
Are you a member of oldGMCtrucks.com discussion boards? There are members there with documentation and GMC knowledge. Some of members here are members there. They might be able to help. Be patient - good luck.
Here, or there, post the size of the GMC.