In 1933, Dean Harper was a 17-year-old high school senior.  His Machine Shop instructor, Clarence Robb, got him a job working at the Gravely factory in Dunbar, WV, afternoons and evenings.  Mr. Robb made all the "experimental" machine parts for Benjamin Franklin Gravely at the factory.  Mr. Gravely, Mr. Robb and Mr. Harper developed the first Model L during 1933-1934.  Their first cylinder head had forty 3/16" diameter "pins" to cool the barrel, but it didn't work well.  Mr. Harper redesigned the head with "webs" and it worked much better.  He did this work at his high school and cast the first head in aluminum.  Although 1-wheel Model D tractors remained in production until around 1950, competition was demanding a more powerful 2-wheel tractor - hence all the work on the Model L.

After graduating from high school in 1934, Mr. Harper went to work full time for Mr. Gravely.  Work on the Model L continued.  The original 2-stroke motor designed by Mr. Gravely, Mr. Robb, and Mr. Harper wasn't successful, so D. Ray Hall (Mr. Gravely's business partner and accountant) brought Eustice Rose back to the company.  Mr. Rose had helped Mr. Gravely design the Model D motor years earlier.  Mr. Rose developed a 4-cycle motor for the Model L.

On July 15, 1937, D. Ray Hall, who had acquired controlling stock in the company, fired Clarence Robb.  Mr. Harper was a foreman in the plant and a good friend of Mr. Robb, so Mr. Harper left, too.  He found work as a machinist in several jobs, including teaching machine shop at Stonewall Jackson High School (1940-1956).  In 1953, he started a side business appropriately named "Harper Machine Shop" located across the street from the Gravely factory in Dunbar.

In 1969, Mr. Harper built the first prototype "Harper" tractor.  He achieved a better range of speeds with less gears than contemporary Gravelys.  He eventually sold the Harper to D. Ray Hall, who renamed it "Mountaineer" and manufactured about 1300 of them in the early 1970's under the company name of United Farm Tools, Charleston, WV.  Harper/Mountaineer tractors can operate Gravely attachments and vice-versa.  Flyers mentioned this interchangability.