"Pancho and Lefty" long ago became more than just a song and something closer to a pop-culture touchstone, particularly in Texas and the Southwest. According to Urbanspoon, you can even dine at Pancho & Lefty's Tex-Mex restaurant in St. George, Utah. Unforgivably, it charges separately for chips and salsa, but still.

Written by the late Townes Van Zandt, "Pancho" originally appeared on the former Houstonian's mordantly titled 1972 album The Late Great Townes Van Zandt, as did "No Lonesome Tune" and "If I Needed You," among others. According to a PBS interview he gave in the mid-'80s, some time after Merle Haggard and Willie Nelson's version had become a monster hit, Van Zandt and his band were pulled over near Brenham on their way to a gig in Houston. The officers let him out of the speeding ticket because the Washington County dispatchers used the handle "Pancho and Lefty" to identify the two cops.

"I realize I wrote it, but it's hard to take credit for the writing, because it came from out of the blue," Van Zandt tells the PBS interviewer. "It came through me. It's a real nice song."

Reached a week or two ago at his ranch near Redding, Calif., Haggard says Nelson wanted to cut the song after liking the version on Emmylou Harris' 1977 album Luxury Liner. The two old friends and legendary country songwriters in their own right still talk once or twice a month or so, Haggard says, noting that they have come to take on a "phenomenal likeness" over the years.

"His bass player died at the end of last year, and mine went into a coma," Haggard says. "We've been married [to the same woman] the same amount of times."

Mostly Haggard, who will turn 76 on April 6, says mostly he and Nelson will "try to hit each other with a good joke."

Nelson sure hit him with a good one for the duo's version of "Pancho." Haggard says he had been staying on Nelson's property outside Austin, working on an album with the Red Headed Stranger. As he remembers it now, Haggard had not slept much in about five days, but finally drifted off on his tour bus somewhere around 4 a.m.

"I had been asleep about ten minutes, and he knocked on my bus," he recalls. "I got up -- anybody else but him and I wouldn't have even opened the door. But I opened the door and said, 'What's going on, Will?'

"I found us a song," came the response.

Even though they had already cut ten or 12 songs, Nelson was sure this was the song for the album, Haggard says.

"I said, 'Boy, that's a great title,' he adds.

Haggard recalls Nelson as having "Pancho" all ready to go, but wanting his partner to come into the studio and cut the song live. Nelson had written Van Zandt's lyrics on a paper sack, and folded it out in front of Haggard.

Haggard resisted at first, he remembers.