The 2006 GMC Sierra 3500 is available as a 2-door, 3-seat regular side. Starting at $27,855, the 2006 GMC Sierra 3500 SL 4x4 Regular Cab Long Box Dual Rear Wheel is powered by a 6.0L , 8 -cylinder engine mated to a manual transmission that returns an EPA estimated The top of the line 2006GMCSierra 3500Work Truck 4x2 Regular Cab Short Box , priced at $ 23,185 , is powered by a 6.0L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated