In 1975, the Mint struck some 66 aluminum cents similar to the over 1.5 million 1974 pieces J2151/P2084.
According to a February 21, 2011 article in Coin World, "all examples melted except two whose whereabouts are not publicly known". The Secret Service says they will confiscate any that appear.
Photo used is doctored from a 1975-S proof example to give an idea of what one would look like.
Photo courtesy of Heritage.