What is the payload of 2004GM 3500 gvw10,000 16ft box truck?

I see these 16ft trucks for sale but none of them can answer me about the payload.
16ft box truck with gvw10,000lb daully

I can’t go and weigh someone truck before buying it. I tried to google it but can’t find a cut answer.

 

2004 gm 16ft

I think 2800lb is the payload?

 

They can haul only 2100lb?
That’s too low for 16ft

G4500 gvwr is 14200. They have the same frame as g3500 but the only difference is the leaf springs right?

so, if upgrade the leaf springs on the gvwr of 10,000. Technical I could increase the payload from 2100lb + 4200lb to approximately 6000lb.
But since the sticker is rated at gvwr of 10,000. It would be illegal to operate this truck because the weight is higher.

Is there a solution to this?

 

What is the difference between g3500 and g4500?

the white one is 10,000lb
The yellow is rated at 14200

what are the differences? Frame? Suspension?

 

How much weight can I haul with this truck?
16ft and the gvw 10,000

I don’t have a truck now so I can’t weigh anything. I don’t have that much of experience to make an accurate guess