PURPOSE: To reduce the size and the weight of a tractor and to facilitate assembly, by a method wherein a gear case is removably disposed between a clutch housing at the rear of an engine and a transmission case, and a right and a left frame are intercoupled through the gear case.

CONSTITUTION: A tractor 1 has an engine 2, a clutch housing 3, and front and rear transmission cases 4 and 5, and frames 6, extended frontwardly, are located to the right and the left on the front side of the transmission case 5. The engine 2 and the clutch housing 3 are supported between the right and left frames 6 through the medium of a rubber mount. In which case, a gear case 9, having a reduction gear mechanism 13, is removably disposed between the clutch housing 3 and the transmission case 4, and the right and left frames 6 are intercoupled through the gear case 9. Further, an external power fetching shaft 14 is rotatably mounted in a protruding manner to at least one side of the gear case 9.