Prod. UM28 - Two Gun Mickey
Nineteen animators are credited: Leonard Sebring, Archie Robin, George "Ol' Flop-Ears" Drake, Nick [George], Jack Kinney, Woolie Reitherman, Don Towsley, Ugo D'Orsy, Louie Schmidt, Paul Allen, pioneer Earl Hurd, Cy Young, Art Babbitt, Ed Love, Ed Smith, Frank Oreb, Fred Moore, Roy Williams and Eric Larson. On IMDb we can read that Ollie Johnston assisted on this. Les Clark is there also credited for animation, but he sure ain't on the draft!
It is available on Disney Treasures DVD "Mickey Mouse in B&W."