I've found these "Spacers" in a few 65/66 cars. These two I just pulled from a 66 GT Convertible. They sit above the front coils. OEM or Aftermarket?
Those are Ford Service number C4DZ-5355-A, called a "Shim" by Ford, with a lot of uses that depends on engine, body style and options. See Ford Car Parts (aka MPC) in the library in text section 53.65, page 22 and on, and 53.66, page 89 and on. The Ford Service number is listed at the bottom of the page. They are used in conjunction with Ford base number 5415, a coil spring insulator.
Jim