searching Kor dramas set in 70s

starts somewhere in 70th  

http://mydramalist.com/1596-rock-rock-rock

http://mydramalist.com/9-friend-our-legend

starts somewhere in 60th

http://mydramalist.com/3095-lights-and-shadows

Thanks :)

There's also the drama Sandglass which spans from the 70s till the 90s. 
And I second Friend, Our Legend, it's a bleak drama, but very good. Although I recommend to watch the movie first, the drama will be easier to follow^^