Not enough information.
Trucks run out of cargo capacity with a 5th wheel before they run out of towing capacity. The truck needs to carry about 20% of the 5er's loaded weight in the bed. Example a 12,000# loaded 5er have approximately 2,500# of pin weight for the truck to support.
GVWR (probably around 9,900# see sticker driver's door jam) - actual trucks weight (load the truck up with fuel and family and head for the
CAT Scale ) = cargo capacity to carry the pin weight.
Good luck.