I am in the process of cleaning a brake distribution valve before adding new o-rings and crush washer. Once in the truck (65) along with the dual master there is the warning light. The two pole sender was with the valve and I can locate a generic light, Not paying $77 for a NOS Ford light. Question is how do I wire it from sender to light? Hard to find info as to whether there is a power source.

Borrowed the photo but this is exactly what I have now soaking to get the piston out.

 

All the wiring diagrams show the power for that light coming from the run side of the ignition switch to the low brake switch then to the light. I have the switch on my truck but I chose not to wire it up but if I ever do I plan on just getting the power from the wire going to the brake light switch. One reason I didn't wire mine was I didn't have that little plug for it an didn't want to go looking for one.

 

That switches the ground. Simply put power to one side of your light, and the lead to the switch on the other.
The plug for that brake switch was put on millions of GM, Ford and Chrysler products, leading to its rarity.

Cosmo

 

There was no Brake Pressure Differential Valve Warning Lamp until 1967, as this was the first year for dual master cylinders.

The 1967 switch is 1967 only.