Heres some basic weight info:
Extended cab long bed dually:
4x4 auto 6828 nv4500 6887 nv5600 7059
4x2 auto 6407 nv4500 6455 nv5600 6669
Regular cab long bed dually:
4x4 auto 6445 nv4500 6477 nv5600 6648
4x2 auto 5990 nv4500 6045 nv5600 6211
Extended cab long bed:
4x4 auto 6568 nv4500 6615 nv5600 6787
4x2 auto 6096 nv4500 6144 nv5600 6310
Extended cab short bed:
4x4 auto 6418 nv4500 6460 nv5600 6628
4x2 auto 5981 nv4500 6048 nv5600 6213
Regular cab long bed:
4x4 auto 6445 nv4500 6477 nv5600 6648
4x2 auto 5990 nv4500 6045 nv5600 6211
Regular cab short bed: (calculated numbers)
4x4 auto 6295 nv4500 6322 nv5600 6490
4x2 auto 5875 nv4500 5949 nv5600 6114
that is including no passangers, no cargo, full fluids
for those running fuel cells the stock tank (35 gallons, i dont know if the ex cab short beds use the 26 gallon tank) holds 250 lbs of fuel. #2 diesel is 7.15lbs per gallon.
should be a good start, but getting your truck down to 5500lbs with you in it, is over 1000lbs.