[Mr70]

YA code was used on early built 70 SS Chevelles too.Plants differed,but usually the Chevelle YA/AO change over was Oct./Nov. 1969.
Other Chevrolet SS models used these too.1969 SS Camaro-Chevelle-Elco-Nova & 1970 Deuce.
Among other things,look for either of these two suffix codes to insure they are for your application.Bring a REAL stainless capped lug nut to insure the holes are not enlarged.