Earlier quoted context omitted.
> The only exception I think is seatbelts since it's illegal to drive a car without wearing one in all but one state. I know in Arizona if the car didn't originally come with seatbelts then you don't have to install them. Used to have a '53 Dodge that didn't have them and it was fine -- kind of freaked out my sister though...
Careful about relying on that, as while state law may not require you add safety equipment such as seat belts, county or city law might. I live in a location in California (which doesn't require seat belts in cars prior to 1965 that didn't originally sell with them), but the local laws require them to be present and utilized while any vehicle is in operation.
We're talking Arizona. Here, you can get away with just about anything, and unless it's blatant, nobody really cares. Sometimes not even then.