Robert in NY gave you the basic information. Here is some info from a site that tells about the 80 JD diesel,
which was the precursor to the Model 830 2 cyl. you were asking about.
<font color=blue> Model "80" Diesel Tractor 1955-1956
Six years after the introduction of the historic "R", its replacement arrived in the 80 Diesel. It was big, weighing 7,850 pounds (shipping weight) stripped down, and 8150 pounds when equipped with options. It was powerful...57.49 hp at the belt pulley, 46.32 hp at the drawbar.
It incorporated many of the most popular features introduced on the 50, 60 and 70 tractors, such as optional power steering, "live" powershaft, Powr-Trol, and a 6-speed transmission.
The 80 Diesel was capable of pulling a 21-foot disk and working up to 125 acres with it in a single day. A big 32-1/2 gallon fuel tank allowed the operator to spend a long time in the field between refueling stops. It had an electric pushbutton fuel gauge.
Technically, the 80 Diesel was a standard tractor with a rear wheel tread of 64-1/2 inches (14-34 or 15-34 tires) or 67 inches (18-26 tires). But these tread widths could be increased to 68-1/2 and 75 inches simply by reversing the rims of the wheels. Up front, an oscillating axle cushioned shocks and provided flexibility for working rough ground. The front tread could be changed from 56-1/2 inches to 63 inches by reversing the rims.
The 80 Diesel was a compactly designed tractor with an 85-inch wheelbase. This provided a high degree of maneuverability.
It was efficient, too. When tested at Nebraska, it set what was then an all-time record for diesel fuel economy.
The 80 was rated at 46.32 drawbar hp and 57.49 belt hp. Nebraska Test No. 567 (1955).
