Impalas were the first to have them I believe (SS) starting in '61, and they were real popular in 62-63, especially with the drag racers... it was an option in any Impala trim, my homey has a 409 '64 SS, hes a white dude though so he dont hop it, but he races every so often, fastest ride I have ever been in... over 1200Hp

hope this helps