Brake Light Indicator In Speedometer Cluster

What feeds the brake light indicator located in the late 60's speedometer cluster?
There is no switch besides the 2 that turn on the brake lights and the wiring diagram doesn't show a connection to the bulb.

 

If you have a brake light indicator in the speedometer, you don't have a late 60's speedometer.

It should look like this with a light for high beams at the top, and then lights for charging and oil pressure on the sides:


There was an optional brake warning light referenced in the in the owners manual, but that was a separate light mounted by itself in the dash. I've never seen one of those in person, so I'm not sure how they were wired up.

Item 6 in the '71 owner's manual:


You must have a newer speedometer. Those would have been triggered by a slider in the brake combination valve. If the front or rear brake circuit fails, the imbalanced hydraulic pressure physically moves the slider and triggers a switch to light up the warning light.

 

Thank you for the reply. The Speedo was a junk yard find. I'll keep my eye out for an earlier one.