It may be different there, but that happened to me when I had my Galaxie and I had the new gear in the glove box and just hadn't had time to install it. I was stopped by a CHP who followed me for about 15 miles and he told me he knew that I was watching him and wondered why I never slowed down. I showed him the gear and told him I was on my way home from working on a problem in San Francisco and was going to change the gear when I got home. He was really nice about it and told me to be sure to drive about 10 MPH slower than the speedometer showed and let me go without a ticket. I doubt if that would happen now with the state looking for money any way they can get it.
Ron