In the official video for the version of “Pancho and Lefty” by Willie Nelson and Merle Haggard, does composer Townes Van Zandt appear? One of the Federales looks very much like him, but I haven’t been able to confirm that it is him. And in the closing scene (at 3:58), where the cast is kicking back over beers and cards, he is playing a guitar and apparently singing the lines, while Willie Nelson (whose voice is singing on the audio track) plays cards quietly in the background.
Yes he does.
I didn’t look to see if he was one of the federales because you didn’t provide a timestamp and the end scene answers the question.
Townes plays a Federale in two scenes–at Federale HQ & in the desert. Then appears as himself at the end…
Townes is the Federale in the background at 1:02, on horseback to Haggard’s left (screen right) at 1:41, close up at 2:39, and then from 3:57 onward in the café (singing and playing his original version).