unilugs

the 67 wagon i just bought has unilug cragars in the rear but it uses a round washer.somehow the wheel must center on the inside of the slots.it doesnt wobble but then again i just bought it and havent driven very far.does this seem right?its a 67 coronet 44 wagon with an 8 3/4...should be 5 on 4.5 right?