With the clutch engaged, it spins the input shaft. In the T-350, 1st gear and 2nd gear are cast as part of the input shaft, and 3-5 are pressed onto the output shaft. Since you aren't moving, the output shaft doesn't move (it's locked to the differential, and thus the wheels). With the input shaft spinning, the 1-2 gears on the output shaft spin, and the 3-5 on the input shaft sit stationary since they are meshed with the output shaft, and the input shaft spins inside them. You also have a bearing on either end of the input shaft that is spinning. The sealed one behind the rear cover, and the roller bearing inside the snout that's in the bellhousing.

So that's 7 bearings that are being spun in the trans, along with 5 sets of gears. Just in neutral.

Oh yeah, don't forget the shift forks! The 3-4 and 5-r forks sit still while the synchronizers spin inside them as they are splined to the spinning input shaft. So if you have a cable problem that is trying to force it into a gear (likely 3 or 4) it'll be riding a synchronizer stop ring on a gear and trying to slow the input shaft down.