The Avalanche is a very interesting vehicle. It can be converted from a four door FULL size back seat pickup to a two seating 8 foot bed pickup.   

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Colorado
Silverado
S-10

2wd = two wheel drive
4wd = four wheel drive
This is the Avalanche 1500 (without Body Package)
It comes in 2wd and 4wd.
This is the Avalanche 1500
It comes in 2wd and 4wd.
This is the Avalanche 2500
Its a little more powerful and comes in 4wd only.
This is the Avalanche Z71 It is The More "Off-road" of all the avalanches and like the 2500 it comes in 4wd only.