Do you have a shop manual for the tractor? Something that has the wiring diagram?
I did an internet search for your model's wiring diagram and didn't get a specific hit (maybe you can dig deeper) but what's below is one of the first diagrams that popped up. I do NOT see DASH LIGHTS in the diagram. The diagram below does seem pretty light so it may be something for an old 135 or 165. Does your tractor have more warning lamps than the 3 that are listed here.