I don't know of anyone that sells original style repl. retainers, but Mitch Romanowski sells beautiful complete repro center caps, including the correct ribbed style for your 70. I have a set on my 68, for 2 years now, and they look great. Were about $38/ea when I bought them. I'll attach a file here of his brochure.
replacement retainers The CARS retainer is for the 1966 through 1970 full-size Buick chrome wheels. I don't know if it will work on the Skylark center caps. However, it may work on the "CARS version" of the 1965 through 1970 center caps for Skylark and GS.
cars sells 2 different size retainers one for 2 inch holes one for 2-1/8 inch holes this was about 3 years ago the parts numbers are similar i also bought their reproduction center caps, and they are nice. while talkin bout C.A.R.S. they sent me the wrong fan clutch, then sent another wrong one. ( both were also used instead of new , one didnt even fit) then stuck me with a restocking fee. was getting nowhere on the phone with them. i called in and had to talk to the owner, and he did straighten it out for me, about a month later. i have heard so much negativity bout them, thought i would post my 2 cents. randy
