All John Deere 790 tractors were designed to the same dimensions regardless of the year that they officially rolled off production lines. John Deere 790 tractors manufactured in 2005 offer a 60.4-inch wheelbase. These tractors are 87.9 inches long unless they have been fitted with a three-point rear hitch in which case they measure 111.0 inches in length. The 790 tractor measures 51.2 inches tall from the ground to the top of the hood. The 2005, two-wheel drive model of John Deere 790 tractor is fitted with 5.00-15 tires while the four-wheel drive models feature 7.00-14 front tires. Both four-wheel drive and rear-wheel drive models of this tractor made in 2005 feature 11.2-24 rear tires.
During years of production, 790 tractors were constructed with the same engine. The John Deere tractor employs a 3TNE82 model Yanmar engine. This is a diesel-fueled, three-cylinder engine. The displacement on this liquid-cooled engine is 81.13 cubic-inches. This Yanmar engine offers 3.23-inch by 3.31-inch bore and stroke and a 18.5:1 compression ratio. The engine fitted into the 2005 John Deere model 790 tractor offers a maximum gross output of 30 horsepower.
Two-wheel drive models of the 2005 790 tractor were constructed to a weight of 1,930 pounds while four-wheel drive models weigh 2,105 pounds. The transmission on these tractors offers eight forward-motion gears and two reverse gears. This tractor features a fuel tank with a maximum 6.3-gallon capacity. The hydraulic system designed into this tractor is capable of holding four gallons of hydraulic fluid. The hydraulic fluid can move through this system at a rate of 5.4 gallons per minute. The hydraulic system on the 2005 John Deere 790 tractor can produce pressures in the range of 2050 psi (pounds per square inch).