The towing capacity on the 1993 Sierra is about 8000 pounds via the bumper pull. The truck with the largest engine is rated for about 9000 pounds.
3500
Max towing capacity for the 2005 GMC Sierra 1500, V8, Regular Cab, SLE 2 WD is 6300 lbs.
towing is 7500lbs
10000 lbs
4000
What are you trying to two
4000 lbs
Look in your owners manual. It has them all listed there. My 2003 GMC Sierra 4x4 with stepside is 8600lbs.
Between 7000 and 7500 lbs
Got the info straight from GM; 2005 Sierra 1500 5.3L Crewcab shortbox 3.73 axle ratio 4x4 is rated at 7400lbs towing capacity.
The max towing capacity is not a question of what engine your vehicle is equipped but what suspension it is equipped with. But check the door jam on the drivers door. All model specific info is contained on this data tag.