Required or requires, either way Pontiac obviously wanted the deluxe wheel covers and the 400 option to be together, I'm guessing you could upgrade or change from there. I'm too young to have ordered this car, but in the 70's there was still some leeway when it came to making changes on the order form, from what I've read, it was almost anything goes in the 50's and 60's. Today, ordering a new car is boing, they have you corralled into taking option packages and colors that you're not too crazy about, there's no way to make it "your" car. I think the hubcap thing will always be a mystery.