Left-hand and right-hand are referenced from the point of view of the tractor operator.
The flat backside of the belt rides on flat idlers; the inside vee rides in v-idlers and pulleys.
These John Deere products use belt part number GX10851 which is 95.87" long, 0.5" wide, HA section, 0.31 thick, 32 deg., KEVLAR
Overall view of the drive belt layout (#1). The engine pulley is off to the right and the transmission pulley is to the left.
The tie rod (#2, yellow) must be disconnected and the parking brake latch handle (#2, blue) must be removed to change the belt. The latch spring extends from a hole in the latch rod (#2, white) to a bracket just forward of the flat idler. The belt can now be looped over the brake latch rod and around the steering shaft (#2, green).
Remove the belt guide from the engine stack pulley and bring the belt around the upper pulley (#3).
Remove the rear v-idler and loop the belt around the transmission pulley. Position the belt in the v-idler and re-install it (#4).
Unhook the front end of the idler tensioning spring from the frame (#5, white) just forward of the steering shaft (#5, yellow).
Route the belt around the tensioning idlers (#6) and re-hook the spring to the frame. The back end of the spring hooks into a notch on the idler arm (#6, blue). The back end of the brake latch spring hooks to the frame at #6, green.
Deere Scotts 1642H diagram (#7). The engine stack pulley is at the right; transmission pulley at left.
Deere Scotts 1642H deck (#8).