Lets set the facts straight. Deere/Hitachi builds contruction equipment( excavators, mining equipment, etc.) John Deere builds the agricultural, commercial equipment, and powerplants that go with them. 2 different entities. See below.....

Deere-Hitachi Company Description
Deere-Hitachi Construction Machinery (DHCM) produces hydraulic excavators in North Carolina and in Saltillo, Mexico. The company sells new and used equipment that includes compact excavators, rigid frame trucks, mining excavators and shovels, and forestry excavators. DHCM was formed in 1988 as a joint venture between Deere & Company and Hitachi subsidiary Hitachi Construction Machinery Co. The companies integrate their marketing operations in the Americas to streamline decision-making, improve customer support, and strengthen both the Deere and Hitachi brand names.

You can read the time line at:
wwwdeere.com/en_US/compinfo/student/timeline_1980.html