I was wondering why no one had mentioned Marshall Grover. I remember really enjoying his "Larry and Stretch" westerns when I was younger. But now I see this was an Australian author
Leonard Frank Meares. Apparently his other pseudonyms include: Marshall McCoy, Ward Brennan and Glenn Murrell.
A link to the first Larry and Stretch on Goodreads - called
Drift!.
Did any of these turn up in America?