Tell dad to be aware that although Ford adds say the F150HDPP has a 3200 lb payload sticker... all that weight can't go in the bed over the trucks small 4800 rawr. The most a F150HDPP cab carry back there before exceeding its 4800 rawr is in the 2400-2500 lb range depending on how the truck is configured. The payload number is a gvwr based payload and comes from front and rear axles together.
Older F150HD had 7 lug wheels but newer models use 6 lug wheels. I'm sure HDPP owners will have some ideas how to determine the newer HDPP trucks.