Yes, here is a picture of the firewall:
http://i1023.photobucket.com/albums/af352/vincentmilone/DSC_0049-2.jpg .
So a 1949 cab would account for the 47-49 tapered grommet.
Is this uncommon/original or not/something to be worried about?
So will the '50 harness be fine?
Do I technically have a 1950 truck, or a hodgepodge?