Chev 2500HD LS model

The Vortec 8100 (RPO L18) is a V8 truck engine. It is a redesigned Chevrolet Big-Block engine 
and was introduced with the 2001 full-size pickup trucks. It retains the same bore centers as 
the old 7.4 L big-blocks, but stroke was upped by 9.4 mm to reach 8.1 L (496 ci) for a total 
of 107.95 mm bore and 111 mm stroke. It is an all-iron engine (block and heads) with two valves 
per cylinder. Power output ranges from 225 hp to 340 hp (168 kW to 254 kW) and torque from 
350 ft·lbf to 455 ft·lbf (475 N·m to 617 N·m). Vortec 8100s are built in Tonawanda, New York. 

GVWR (Gross Veh Wt Rating) 9200 lbs
 2WD Payload is...         3585 lbs
(4WD payload is only...    3308 lbs)

  What the truck is rated at with passengers
  and load all wt bearing down on the axles,
  suspension, tires, etc.

  Has nothing to do with what it will pull.
  Just the wt that can be placed on the
  suspension, springs, shocks and factory
  supplied tires before it is over weighted.

FAWR (Front Axle Wt Rating) 4410 lbs
RAWR (Rear Axle Wt Rating)  6084 lbs
Sum of both is...          10494 lbs

  Note how the sum of these wts exceeds the
  GVWR because the actual axles are stronger.
  The weak link is probably the tires which
  reduces the GVWR.

The curb wt of the 2500HD 2WD LS is 5615 lbs
  (vs the 4WD curb wt of 5892 lbs).  When
  added to the 3585 lb payload rating you
  get the 9200 GVWR (as noted above).

The Maximum Towing or 
GCVWR (Gross Combined Veh Wt Rating) is 12000 lbs

  This is what the engine, transmission,
  drive line, rear end gears and/or brakes
  are able to handle when loaded down and 
  towing a trailer, etc.  It is the complete
  towable load.  However, this all depends
  on the type of hitch used and trailer
  brakes, etc.  With good trailer brakes
  and hitch the 2500HD is safe up to 12000 lbs
  (or more as we all know these numbers are
  fudged some).

  When I haul the car to a race I am hauling
  apx 5700 (trailer and car) + 400 (two people) +
  250 (gear/tools) + 5615 (truck wt) + 182 (fuel) =
  12147 lbs!!!  Just a tad too much.  But it
  still tows everything without breaking a sweat
  at 70 mph up over the pass south of Ashland
  into northern California.  With just me in the
  truck it is right at the 12000 lb limit. :)

Class 4 Trailer Rating 8500

  This is what the trailer is rated to haul
  including it's own wt (trailer plus load).
  The trailer weighs 1860 lbs.  The tire
  rack weighs another 150 lbs.  The car
  weighs around 3480 with driver and apx
  3300 w/o and a full tank.  With 390 lbs
  of tires on the rack and some gear stowed 
  in the car it scaled out at 5700 trailer wt.
  1860 + 150 + 3300 + 390 = 5700.

The truck hitch is rated at 7500 lbs w/o 
weight distributing hitch platform and
12000 lb with wt distributing platform.
I run load levelers which help a lot!

It has a tonge wt rating of 1000 lbs and
1500 lb respectively.  When the car is
loaded and tires are on the rack it
scaled out with a tonge wt of 380 lbs.
The hitch is plenty strong to deal with
both the loaded trailer and full tonge wt.

-----

To see how this might compare to a full 1 Ton 
without a crew cab and with dual rear wheels
you can go here.  It does have a GVWR of
11400 lbs.  Payload increases from 3585 to 
5559 lbs because of the two extra rear tires.

Note however that the Max Towing rating is 
still the same.  It will haul more on the 
axles/suspension but not any more in terms 
of GCVWR.  Same engine and drive train means
no more hauling capacity without breaking
the drive train parts...