GMC T-Series 2007 Owner's Manual page 78

Six-Speed Transmission
The transmission has gears that automatically
synchronize when you shift up or down. Choose
the gear which will maintain the road speed
you want while keeping the engine above
two-thirds of the governed speed. When the
engine speed drops below two-thirds of the
governed speed, shift into the next lower gear
before your engine begins to become sluggish.
When you shift down, be sure to double-clutch
if required.
See "Double Clutching" later in this section.
78
® ®
Eaton Fuller Nine and Ten-Speed
Non-Synchronized Manual
Transmissions
If your vehicle has one of these non-synchronized
transmissions, it is naturally somewhat
complicated.
The following are driving tips:
•
Always choose an initial starting gear suitable
for the load and terrain.
•
Always use double-clutching procedures when
shifting.
•
Never move the range shift lever to the LO
speed gear position after HI range preselection,
or anytime the transmission is in the HI range.
•
Never move the range knob or lever with the
shift lever in NEUTRAL while the vehicle is
moving.
•
Never make a range shift while moving in
REVERSE (R).