Unless Majestic has changed, you have what is known as the “ hub cap” design. You need the design that caps are held on by couplers nuts. In this link look at.... Over-The-Lug Mounting Style (Style 3) The ones you see along the road that have fallen off are the hub cap design. Spring tension keeps them on till the spring tension is shot or you hit a curb.
https://images-na.ssl-images-amazon.com/images/I/81ymjWqfp0S.pdf Be sure you’re looking at “Over-The-Lug Mounting Style” in this link.
Got mine on amazon, after recommendation from IAMICHABOD, who is active on here. Very happy and they look great. See if IAMICHABOD still has contact info. If not, I have it at my house, but in Yuma right now.
Some people think they have to re-do their extensions of rear valve stems. Or cut a groove in wheel simulator them to get extensions on. I went to a tire shop supply place and they sold me what worked.
If you buy direct from Pacific Dualies you'll pay a lot more for some reason.