Hubcap/Rim rivets ?

Does anyone know where to get these at ?
(They're the ones that mount on the rim itself and you press on the hubcap)
I do have the proper rims.

 

http://reoriginals.com/ProductImages/B0010X.jpg
here's a link I already ordered 3 of these but they're to short/small

 

I just found some other rims from the same general brand as my Plymouth.....in
other words, Chrysler product rims......and drilled out the rivets. Then attached
the clips to my wheels that needed them. Got the needed size - even though a
couple looked slightly different. I see you have a DeSoto.....so can you find
any other 40s or 50s Mopar rims to "borrow" some clips from??