These were soon followed by the model 5010 standard introduced in 1962. The 5010 was the first two-wheel drive to exceed at the PTO and drawbar. Designed for the western wheat-lands, the 5010 was never available as a row crop model. In 1963, the 3010 and 4010 were replaced by the 3020 and 4020. The 4020 is one of the most popular tractors Deere & Company has ever made. The year 1965 brought the 5020 standard, which was the industry's most powerful two-wheel-drive model, along with the 1020, 2020, and model 2510. By 1966, sales of the 4020 accounted for 48% of all John Deere tractor sales. Also that year, the row crop version of the 5020 was introduced.