An improved, multiple substantially identical countershaft assembly (16, 16A), change gear transmission (10) having at least two (20, 20A) countershafts is provided. The input gear (14) and each mainshaft gear (42, 44, 46, 48) is constantly engaged with a countershaft gear (24 and 24a, 26 and 26a, 28 and 28a, 30 and 30a, 32 and 32a) carried by each countershaft and all or substantially all of said input gear and mainshaft gears are provided with a number of gear teeth not evenly divisible by the number of countershafts whereby the level of noise generated by the meshing of the gear teeth is minimized.