The original cotton covering was a yellow or "oak" color. There are many different tracer markings. Sometimes the wiring diagrams in manuals have the covering color and tracer descriptions. If you are just trying to get a SWAG, below is an image of a nice reproduction harness made by Vintage Wiring of Maine.

[img]http://www.surfacezero.com/g503/data/3176/medium/IMG_71981.JPG[/img]


1941 Chevy 1 1/2-ton WW2 4x4 dump truck
In the Stovebolt Gallery
Lots more pictures