I will be doing one on a '53 3100 soon, and I plan on wiring the harness to the gauge cluster and ignition switch on the bench, then install the pre-assembled works into the truck.
I am pretty sure that was how it was done on the assembly line. If you ever looked at the back of an original gauge cluster with original cloth wires on it, you will see how impossible it would be to make it look like that while on your back, bent like a pretzel.
Carl
