This Beechcraft 18 was originally built during WWII as an AT-11 bombardier trainer. After the war, Beech converted a large number of AT-11s to private and corporate aircraft. Glenn W. Peel from Newkirk, Oklahoma and Irv Hardman hailing from Hill City, Kansas, bought the plane in 1955. Peel first flew the 18 into Hill City from Hoisington, Kansas. It became the corporate aircraft of Jet Drilling Company. Later, JDC was based in Denver. Peel and Hardman drilled in the Four Corners area with a big triple rig shown in the painting.
JDC owned the plane until 1960. I was sort of floored to find Glenn and Irv's Beechcraft 18 survives as a "restored" C-45 at the Selfridge Field Museum in Michigan!