'Pancho and Lefty' is today's KLAW Classic and it was written by singer/songwriter Townes Van Zandt, and is considered to be his most enduring song. 

Van Zandt actually recorded it himself in 1977, along with Emmylou Harris that same year, but it didn't reach the top of the country charts until the duo of Merle Haggard and Willie Nelson recorded it in 1983.