I found a leak on the back side of the fitting that comes out of the intake and goes to the auto trany. It was not obvious or easy to find. I know there must still be more leaking somewhere in my headlight system but it is on the list for one of these days... keep checking one section at a time. You can also check/troubleshoot with the car off using a vacuum hand pump w/ integral gauge (one of the best tools I have bought).

We just bought the white 71 Vette shown in my signature about 2 weeks ago and there is a vacuum leak somewhere in the headlight door section of the system.  I haven't had time to find the leak yet, but it can be a pain in the pinfeathers since every component in a C3 is put in with a shoehorn!  The last 77 Vette had a problem in the headlight vacuum system and after discovering that there wasn't any guidance on how to troubleshooting the system, I did some research and wrote my troubleshooting guide.   proracr38723.8004976852

Here is a link for the parts and conversion instructions for the electric motors.
http://www.vetteweb.com/tech/0408vet_c3lites/

Scott

 I put electric motors in my 73. There is a guy out there selling them. He is just selling the brackets, you still have to get the motors and the module. I made myown brackets out of 1/8 aluminum it takes a while to figure and bolts to 2 of the holes where the actuator is mounted. I used 93-96 trans am motors and got the module out of it with the wiring 'local boneyard'.  The headlights can be operated by just a toggle switch. But if you want to take it to another level us a head light switch out of a c4. It has an extra spade terminal that operates the module for up and down and your current harness will plug into the c4 switch.Once the brackets are made the link on the motor has to be drilled out to the pin that all the springs are mounted to. Takes time but I can count on my headlights at the pull of a switch.30 feet of vacuum hose is gone and about 16 sources of potential leaks are history