The dealer should be able to find out for you easily.  If not call GM or "test" drive it to a scale.  My bed/welder/tools added about 3100 lbs to mine but my bed is built ridiculous heavy.

Will depend upon the construction of your flatbed, relating to how heavy duty and custom it is.  And I agree with the other response, I would figure about 3500 on all your added gear when all geared up.  That way you know you have some fudge room for extras when needed.

Rough estimate for a one ton 4X4 with crew cab, dually, and a flatbed; 6000 should be high but again, depends on the bed, amount of fuel, bed mounted tool boxes, etc.

Then, are you planning on pulling a trailer, RV or for equipment/supplies?  The tongue weight of that will be considered when going across any scales.

Definitely check with a dealer or take it across the scales.  You can find scales all over the place, private and state.

Have a Great Day,  Brent

Guessing that after the bed is on, a standard store bought bed the truck would probably weigh in the 8-9k range.

My personal Truck, a 2003, Ford, 7.3L Powerstroke, 4x4, supercab weighs in at 6400lbs.  No flatbed just a pickup.  Checking Google might help.

If you build your bed right, you will be under 10k with your machine and tools. Don't do like the vikings and kill your truck. I had an 04 max, and I stayed under 10k unless I had a passenger. Full dress, all the extras.

I weighed my rig today, 9920 lbs. It is a Dodge 1ton with a flat bed, welding machine and leads, one set of bottles, typical tools (wrenches, grinder, welding rods, chains, jack, etc.) and 3/4 full of fuel.
If I did not have anything to do I would build a lighter bed.

Floyd