The John Deere GP was a general purpose row crop tractor that was produced from 1928 to 1935. It was originally called the Model C, but there was a lot of confusion between it and the Model D. Since International was having success with the Farmall, John Deere decided just to call it the GP in order to better their chances of competing. The GP had a fixed front axle that straddled three rows. It also had two 14-inch plows, and weighed 3,600 pounds.
John Deere’s GP was a two-wheel drive tractor with manual steering. It had a two-cylinder kerosene engine that was liquid-cooled. The original GPs had a bore and stroke of 5.75×6 inches, a displacement of 311.6 ci, and 900 rated RPMs. In 1931, the engine was improved a bit. A water-injection system prevented a knocking sound that came with the use of low-quality kerosene. It now had a bore and stroke of 6×6 inches, a displacement of 339.3 ci, and 950 rated RPMs.
The GP used a three-speed unsynchronized gear transmission that had one reverse speed. The top speed in third gear was 4.1mph. With the original engine, the GP had a maximum belt power of 24.97hp, maximum drawbar power of 17.24hp, maximum drawbar pull of 2,489 pounds, and maximum belt fuel use of 3.5gallons an hour. Once the engine was improved, the maximum belt power was 25.36hp, the maximum drawbar power was 18.86hp, the maximum drawbar pull was 2,853 pounds, and the maximum belt fuel use was 3.4 gallons an hour.
While the GP was the most popular and most manufactured, there were other versions. The GPWT had a wider tread. The rear axle was 76 inches across, and the tractor had a tricycle-style front tire. The GP-P, created specifically for use in potato fields, was similar in style to the GPWT but had a 68inch rear axle. The GPO was created for orchard-use. It was lowered and had fenders.
The serial number for the John Deere GP is located under the gear shifter. Production year corresponds with the serial number as follows: