Enables a Holden caliper to be spaced to take a wider disc rotor.
On HT, 1969 to 1970 models, the V8 takes a wider rotor (RDA3) than the 6 cylinder (RDA2). These spacers were original on this model but can be fitted to the 6 cylinder calipers so the wider rotors (RDA3) can be fitted.
Also standard on all HG 1971 to 1972 with disc brakes.
The same applies to-:
LC Torana GTR XU1 1969, 1970, 1971, 1972.
LJ Torana GTR XU1 1972, 1973, 1974. (RDA4 = 16mm Thickness)