On this page you'll find the exact dimensions for the GMC Sierra Extended Cab 2500 HD & 3500 generation 3, made from 2007 to . Below we'll list the dimensions for this pickup from verified sources. First, let's make sure you have the right dimensions in front of you:

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Dimensions in tables

Sierra truck bed dimensions (Extended Cab)

Truck bed dimensions	Standard Box (6.5')	Long Box (8')
Volume (cu. ft.)	56.9	70.7
Length at floor	78.7	97.6
Inside height	19.5	19.5
Width at wheelhouse	50	50
Maximum width at floor	64.8	64.8

Wheelbase of the Sierra:

Wheelbase	Length (inch)
Standard Box (6.5')	143.5
Long Box (8')	157.5

Exterior dimensions of the Sierra Extended Cab:

Dimension	4x2	4x4
Overall length - Standard Box	227.7
Overall length - Long Box	246.6	246.6
Height - Standard Box (6.5')	76.2	76.5
Height - Long Box (8')	76.3	76.7

Exterior width of the Extended Cab:

Exterior width	4x2	4x4
Overall width - Standard Box (6.5')	79.7
Overall width - Long Box (8')	79.7	96.1

Extended Cab miscellaneous dimensions

Miscellaneous dimensions	4x2	4x4
Min. ground clearance - Standard Box (6.5')	8.5	8.8
Min. ground clearance - Long Box (8')	8.7	8.8
Step-in height - Standard Box (6.5')	24.4	24.6
Step-in height - Long Box (8')	24.9	24.9

Interior dimensions

1st row dimensions	Extended Cab
Head room	41
Shoulder room	65.2
Hip room	61.4
Leg room	41.3
2nd row dimensions	Extended Cab
Head room	38.4
Shoulder room	66.3
Hip room	61.5
Leg room	33.7

Turning circle of the Sierra:

Turning circle:	Kerb-to-kerb	Wall-to-wall
Single-wheel pickups	46.8	50.8
Dual-wheel pickups	50.7	50.7