The 2006 GMC Sierra 2500HD is available as a 2-door, 3-seat regular side. Starting at $32,675, the 2006 GMC Sierra 2500HD SL 4x4 Crew Cab Long Box is powered by a 6.0L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated The top of the line 2006GMCSierra 2500HDWork Truck 4x2 Regular Cab , priced at $ 21,825 , is powered by a 6.0L , 8 - cylinder engine mated to a manual transmission that returns an EPA estimated