Hubcaps for 16.5 wheels

[zac]

I've got 3 16.5x9.75 steelies, two have the nubs on the outside of the inner ring to hold caps in the conventional way (the one on right in the pic, for example). And I have one that appears to have no way of attaching a hubcap (on the left). And I have seen these wheels that have clips to hold caps (silver painted one). What's the deal? Can you even find or get the caps that were meant to be held on by the clips? Does anyone have a pic of what it would look like? I'm having the worst time trying to put a set of these together.