possible custom spoiler for corvairs?

this spoiler iv seen on many different muscle cars but it seem like its always custom for corvairs and part of a kit or stock with other cars

http://www.scottlewisonline.com/images/69_camaro_garnet_red_4_spd_tx_2.JPG

(best pic i could find online, i don't own this car)

im just wondering if anyone else knows anything about it because i would like to put one on my 66