My red/yellow sticker says 1,320lbs, and I've got a pretty loaded-up Limited. There was a thread on here a couple of months ago where the poster said they put 4,020lbs in the bed, and made it home. IIRC, it was a 10-mile trek across town, and he said that 55-mph lane changes were interesting.
Your best bet is to go to a dealer and check out the payload sticker for yourself, or ask one of the salespeople there to check it for you and report back.
All that said, I had me, my mom, and my toddler in my cab, with a 100+lb quartz countertop and 10 80lb bags of stone dust in my bed, and the truck didn't act like anything was back there.
-John