In 3rd Gear

Hydraulic pressure is applied to the 3rd clutch, then the 3rd clutch engages the intermediary shaft 3rd gear with the
intermediary shaft.
The mainshaft 3rd gear drives the intermediary shaft 4th gear via the intermediary shaft 3rd gear and the 3rd clutch.
The intermediary shaft 4th gear drives the countershaft 4th gear and the countershaft via the mainshaft 4th gear.
Power is transmitted to the final drive gear, which in turn drives the final driven gear.
As the final driven gear turns the front differential, power is transmitted through the transfer drive gear to the transfer output shaft that drives the transfer hypoid drive gear/shaft and the transfer output shaft (hypoid gear).
Hydraulic pressure is also applied to the 1st clutch, but since the rotation speed of 3rd gear exceeds that of 1st gear, power from 1st gear is cut off at the one-way clutch.

Fig 1: Transmission Power Flow Diagram - 3rd Gear

Courtesy of AMERICAN HONDA MOTOR CO., INC.