There are no F150 models in the US that weight 7700 lbs or even close to it. The heaviest one is 5517 lbs.
https://media.ford.com/content/dam/fordmedia/North%20America...
https://media.ford.com/content/dam/fordmedia/North%20America...
PS: Actually, the limits for the basic German driver's license (B) are: Max GVWR of 3500 kg. With trailer, if GTWR not above 750 kg, no GCWR restriction, otherwise max GCWR of 3500 kg.
There's an extended license (BE) for max GTWR of 3500 kg and no GCWR restriction. (Max GVWR still 3500 kg.)
https://www.adac.de/verkehr/rund-um-den-fuehrerschein/klasse... (German text).
The F250 line tops out at a curb weight of ~7500 lbs with a GVWR of an even 10,000.