The 2003 GMC Sierra 3500 is available as a 2-door, 3-seat regular side. Starting at $31,400, the 2003 GMC Sierra 3500 Base 4x2 Crew Cab is powered by a 6.0L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated The top of the line 2003GMCSierra 3500SLT 4x4 Crew Cab , priced at $ 36,550 , is powered by a 6.0L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated