The whole trumpet of the rear axle broke of, the wheel, brakes,planetary gears are bolted in/on the trumpet. The trumpet itself is made out of cast iron which is strong but also quit brittle, it breaks fairly easy when it encounters a lot of stress(big forces). Due to the reciprocating motion of the backend of the tractor the trumpets do encounter a lot of stress ! Not only the trumpets don”t like the up and down motion, the whole drivetrain does not like it. If the trumpet wouldnt have broken of it might jumped out of gear or broke something else in the drivetrain. This tractor is one of the “good old ones” where you basically take a standard John Deere tractor, strip it and use the cast iron components to built a tractorpuller(rearend,gearboxhousing,clutchhousing etc.) Nowadays its more likely to see a “full race tractor” which does not use standard cast iron components but lighter and stronger components such as a rearend of a lorry/truck and everything is secured in a tubeframe or an other type of frame instead of the engine block,clutch housing, gearboxhousing and rearend all “hanging together”.