Now for 1975, there are none. The mint had special permission from Congress to mint the 1776-1976 quarters in 1975 as well as 1976. There are no 1975 1/2 dollars either. You can stop looking for a coin that does not exist.
Source(s):
46 years a numismatist, Red Book A Guide to U.S. Coins
ETA...
This is the info I found:
The U.S. did not strike quarters with the 1975 date. Dual-dated quarters bearing the date 1776-1976 were issued during all of 1975 and 1976 to honor the Bicentennial.