If your vehicle is a pickup with a 9' box and single wheels, I doubt that lights were were an option because it never fell within the 80" requirement. However, this cab was used on trucks that were over 80" wide. Texas required a light on each side which were known as clearance lights. The 3 lights in the middle are known as identification lights and were not required in Texas. Other states had other regulations. Back then, trucks engaged in interstate commerce were regulated by the ICC.
If you want lights, I would follow current regulations. Clearance lights on each side and 3 identification lights no less than 6" and no more than 12" apart.
This is a pretty simple bulletin on what is law now in the US and in Canada.
http://www.nhtsa.gov/cars/rules/standards/conspicuity/TBMpstr.html
