What does 7700 signify?

So what's different between an F-150 and one that is dubbed F150 7700? Normally those big numbers can refer to the engine size (like a 300ZX, B2300, or Vortec 3800, etc...) but surely Ford doesn't have the nards to stuff a 7.7L engine into a half ton (one can only hope....).

i think it means heavy duty i dont think the number really stand for anything, i knew what it meant but i forgot!

Stands for its GVW. It means its almost a 3/4tonne as apposed to the 1/2tonne

Thanks- makes sense. So it's 3/4 of a 3/4 ton.....

In 1998 Ford produced a light duty F250. Actually it was the only 250 produced as a 98. The heavy duty 97's were carried into 98 as a 97 model and the 99 super duty's were intorduced early. After the 98 model year the designation was changed to F150 7700. If I remember correctly the option for it was payload pkg #1 and #2