It all does depend on your local Laws. My first recomendation would be to go down to your Local Library and Look up ALL of the Automotive Lighting Statutes that are on the books for your City AND State. Make yourself copies of them, and take them home with you. Once you have the actual Laws in front of you, it allows you to really take a good close look at them and formulate your plan to build your car within the laws.
In My State, (Arizona) The law states: “A person shall not drive or move a vehicle or equipment on a highway with a lamp or device on the vehicle that is capable of displaying a red or red and blue light or lens visible from directly in front of the center of the vehicle. Lights visible from the front of a vehicle shall be amber or white. This section does not apply to an authorized emergency vehicle or a vehicle on which a red or red and blue light or lens visible from the front is expressly authorized or required by this chapter.”
Now, the important part of that Law is the part where is says “Capable of displaying”. My Ecto-1a has Both RED and BLUE in the front of the lightbars. So, to keep the car legal, we have made it so the lights are not “Capable” of displaying light when we are on the streets. I have several Master Kill switches, and they are wired in such a way that they ALL have to be switched on in the proper sequence before the emergency lighting on the car becomes active. Most folks with Vintage Ambulances and Police cars have a Master Lighting Switch mounted Under the Hood that ALL kills power to ALL of the emergency lights. That makes it very easy to PROVE to a Police officer that the lights are not operational. (POint to the plainly labeled switch in the OFF position and let them know that its your master Power switch for the lights) Also, We have made Lightbar covers to actually cover all the emergency lights when we have the car out on a public road. Even though the lights are wired to not be capable of displaying light, we have covered them as an extra precaution. (And also To SHOW the local police that we are not trying to break any laws)
Please keep in mind, that an Ecto-1 or a 1a replica is a HUGE visible vehicle. You CANNOT hide it. And Police officers talk to all of the other officers they work with. If they even THINK you are screwing around with lights, word will spread and you wont be able to get gas witout being watched and hassled. Also, Not every cop out there is going to be familiar with the little parts of the law that pertain to the lights on your car. They are going to see Light bars and Assume that they are illegal. They have to know all of the vehicle laws, and cant be expected to remember every detail of every law. And There are cops that WILL Ticket you for the lights, and figure that the courts will sort it out.. IF That happens, BE POLITE, DO NOT ARGUE with the cop, remain friendly, and take the ticket. And then take all your paperwork to fight it in court. If the Cop asks you to Turn the lights ON, DONT!!!!.. That is entrapment. They cannot MAKE You turn the lights on to prove that they do or do not work. (Side note: DO NOT EVER run the lights on a public street. If you do that, you ARE BREAKING THE LAW, and you have no way out. And in most states, they can charge you with Impersonating an officer which means you WILL go to jail and you could lose your car, Cops are VERY Serious about Restricted lighting)
Like it or not, there is a HUGE Responsibility associated with driving an Ecto Replica. Everyone is going to notice you, and if you screw up, EVERYONE is going to remember.. I'm not trying to imply that you are a bad driver. I'm just letting you know that once you get behind the Wheel of an Ecto, you better Drive PERFECT cause everyone is going to be watching.. It was an interesting lesson for me to learn when I first fired up the car. Its literally like driving in a fishbowl..
My suggestions to you are as follows:
1. Learn your Local vehicle lighting Laws, and KNOW Every little part of them that might even possibly be relevant to your Replica.
2. Build your car from the beginning to comply with ALL of the Laws.
3. Build in at the very least, a Master Kill switch under the Hood, and MAKE Sure that switch is OFF before Starting that car to take it any where.
4. Make yourself Light Covers. Its an extra safety precaution for you, and it protects the lights from dirt and grit and rock chips.
5. Volunteer your time and your car to some public activities that your local Police or Sheriff sponsors. (We have taken our Ecto to a Halloween party that the Sheriff sponsors.) Its alot of fun for you. You get to talk to the Officers and show them your car in a controlled legal environment, and is shows that you didnt build the car to cause trouble with it. Its good PR for you and your car, and can go a long way to making life with Local Law Enforcement easier on you..
6, Always drive your replica as if you were being watched and followed by the Cops. You have a responsibility to not only drive legally and safely, but there is also an expectation to represent the GB franchise in a positive manner as well. AND, everything you do on the road will reflect on every other person in the country that owns a replica. We all need to look out for each other when we are out on the roads.
If you have any other questions, or you would like to talk more about Ecto's or Replicas, Dont hesitate to E-Mail me directly. I always enjoy talking Ecto's..

TheEcto1a