The Crossover GP

When most people hear the term “crossover,” they think of an item that is somewhere between two things. Often in the tractor game, a crossover is a piece that is a small point in between the production of two different models. This latter definition best suits the “crossover GP.”


In the beginning, Deere and Company created the “GP” but eventually, the engineers, dealers, and farmers discovered that not all was good. While the little flathead could, in most cases, get the job done, there were some problems. The early tractors with the 5-3 / 4 inch bore used a water injection system to prevent pre-detonation. This was actually a fairly common answer to a fairly common problem in the early years of tractors. Due to the type of fuels being used, coupled with engine and carburetor technology, pre detonation could occur. The answer at the time was to introduce a small amount of water, usually straight from the coolant, into the carburetor or manifold. This meant that while working, the tractor often needed to have the radiator topped off. Remember Mr. Thinker’s line about coolant having bullheads swimming in it. No joke really—the answer to a need for water in the field was often the nearest pond, stream, or puddle. As you can well imagine, this eventually caused a problem with the injection system plugging.


It is to Deere’s credit that rather than just curing the problem by adding a 1920s’ technology filter, the company instead chose to make improvements to the tractor to eliminate the need for the problematic system. To begin, the tractor’s bore was increased to six inches. A new manifold was designed that would send the exhaust out on the right-hand side of the tractor. This new manifold also served to carry more of the heat away from the carburetor. The carburetor, which previously was connected to the manifold from the front of the tractor, was now connected from the left side. Attached to the carburetor was an item that made the crossover “GP” so instantly recognizable—the air intake pipe, which took air from the air cleaner (now located between the head and radiator), turned it 360 degrees and then to the carburetor.

Right side exhaust of a crossover.

The first batch of crossover “GPs” were all wide treads, likely because they were the biggest seller in the south, an area where the water injector plugging problem was most severe. The first “GPWT” crossover was tractor number 402040, which was built April 18, 1930. The last might have been serial number 402444. At least that’s what the parts catalog would have you believe. But of those tractors whose serial numbers would lie in between, 123 were rebuilt into later style tractors and renumbered and a dozen or so serial numbers weren’t used for anything while six tractors were converted to “GPOs.”

Carbs on crossover “GPs” had lettering that was squared off and does not follow the contour like on later carburetors.

Beginning in May of 1930, Deere made the same changes to the “GP” standard tractors and 68 of them were built beginning with tractor number 222345. This time the “old style” 5-3 / 4 inch bore “GP” standards were being built at the same time with serial numbers intermingled with the crossovers. A total of 68 “GP” standard crossovers were built, ending with tractor number 223801, with the bulk of them being shipped to Canada.

Here is one of the wide tread crossovers.

It is not known whether the crossover tractors were somewhat experimental units, testing how six inch bore tractors could operate sans water injection and a redesigned carburetor and manifold, or whether Deere had intended to keep them in production indefinitely (but soon deciding a better system was needed). In any case, a new design was introduced for the 1931 model year which incorporated an air filter, stack and precleaner in one unit.


Of the 340 or so total “GP” crossover tractors that were built between April 18 and August 15 of 1930, it is likely that no more than a couple of dozen are left. Between changeovers at the factory, updates in the field and natural attrition, it is likely that there are no more than a couple dozen left. But are they all now in the hands of collectors or are there a few out there wasting away while waiting for you to come and rescue them? Could be.