This is the strangest tie-in I've ever come across - it's not based on a TV series or film, well not officially. But the title's Leatherwood, the main character is Cliff Leatherwood. And is the resemblance on the cover to a certain Clint Eastwood a coincidence?
I've not read it, picked it up amongst a pile of secondhand books but it amuses me but the plot, involving a freedom fighter called Benito Juarez makes it sounds as if it's aiming for the feel of the dollar films.
It was published by Powell Books of California in 1970 and is credited to the name Stack Sutton. It was probably a house pen-name. The publisher's
It shows how vibrant the paperback business was in those days - books like this would have probably turned a tidy little profit.
WESTERN RELATED -There's a great interview with Black Horse Writer, John Paxton Sheriff over on Western Fiction review