It's actually not even called that. The below is from Ford's vehicle builder. There is no such thing as a "Heavy Duty Payload Package" for the F-250 or the F-350. You would not need the Trailer Tow Package below on a F-350 and it's not even offered. You are good to go.
F-250 Trailer Tow Package - High Capacity
• 6.7L Power Stroke® Diesel Engine
• Trailer Brake Controller (TBC) – XL SRW
• Increase GCW on diesel engine from 23,500 lbs. to 30,000 lbs.
• Upgraded axle
Not available with:
• 10,000 GVWR/9,900 GVWR Package
• Pickup Box Delete