GMC 2010 Sierra 1500 Crew Cab Owner's Manual page 443

The correct hitch equipment helps maintain combination
control. Most small-to-medium trailers can be towed
with a weight carrying hitch which simply features a
coupler latched to the hitch ball. Larger trailers may
require a weight distributing hitch that uses spring bars
to distribute the trailer tongue weight among the two
vehicle and trailer axles. Fifth wheel and gooseneck
hitches may also be used. See Weight of the Trailer
Tongue earlier in this section for rating limits with
various hitch types.
If a step-bumper hitch will be used, the bumper could
be damaged in sharp turns. Make sure there is ample
room when turning to avoid contact between the trailer
and the bumper.
Consider using sway controls with any trailer. Ask a
trailering professional about sway controls or refer to
the trailer manufacturer's recommendations and
instructions.
Body to Ground Distance
Front of Vehicle
When using a weight-distributing hitch, the spring bars
should be adjusted so the distance (A) is the same after
coupling the trailer to the tow vehicle and adjusting the
hitch.
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