The 2012 GMC Sierra 3500HD is available as a 2-door, 3-seat regular side. Starting at $34,760, the 2012 GMC Sierra 3500HD SLE 4x2 Regular Cab Dual Rear Wheel is powered by a 6.0L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated The top of the line 2012GMCSierra 3500HDDenali 4x4 Crew Cab Short Box , priced at $ 49,715 , is powered by a 6.0L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated