Darrell,
I too have a 1949 3100 1/2 ton pickup. When I did my wiring I found it much easier to remove the speedometer, cluster gauge, radio speaker grill etc. and work with these components removed. Pass the wires through the gauge holes. I then worked from the left to the right starting with the headlamp switch, next to the gauge cluster and then the speedometer, re-installing each component of the dash after you have completed all connections. I didn't secure everything tight until I was sure all connections were made including the ignition switch and any accessories added. (ie: cigar lighter, glove box light, radio, etc.) Hope this will be of some help.
Tim
