What? You've never heard of it? Neither have I! Luckily a viewer of this website told me about his. There were only two made, #10859 and #10860. If you know where the other RI is, email me.
See Pictures, here!
Both RIs were built in late 1951. In November they were tested for a couple weeks and different front ends were tried, and a bulldozer blade (from the American Tractor Equipment Co.) was fitted on the frame. They later were shipped to Little Rock, Arkansas.
The RI would have been a great industrial tractor, except it had weak PTO drive gears. This made them unsuitable for PTO driven scrapers. This was corrected in the number-series tractors, and the later series' made great tractor/scrapers, finally evolving into the mighty 840.
You can see a great website about the John Deere R at: www.twocylinderdiesel.com It is full of great information!