That 71 was produced towards the end of June 1966. Also welcome to OCC, glad to have you here. We have many great and knowledgeable people here that can help you with most anything. Oh before the others chime in, we really love pics of cubs here.
Take a look thru all of the different areas here at OCC especially the Tractor and Implement Library sections. Most of the information you will probably need including Serial numbers by months and years, Kohler engine manual, Cub 71 service manual and owner's manual. You can download the manuals and print them out.