This article is for the 1999-2010 Ford F250, F350, and F450 Super Duty. For the 2011-2015 Ford Super Duty please see this off-website writeup on the Ford Truck Enthusiast Forums.
So you need legal seating for three people in the front row of your F250 / F350 / Super Duty. It's not going to be as simple as purchasing a jump seat and putting it in. You're going to run into a little issue. If your Super Duty came with a console originally you probably have arm rests attached to your seats. That arm rest is exactly where part of the jumpseat will be, so the arm rest has to be removed.
The arm rest cover slides off fairly easily, and underneath there is typically a T45 Star Bit Bolt. After you remove the bolt you'll see two small holes underneath. These will be there, there's nothing you can really do about it without going to an upholsterer or purchasing new seats. You'll likely spend about $200-300 at an upholsterer to have a cloth panel replaced, and $300-400 to have a leather panel replaced. The good news is that the jump seat should cover the most of the holes.
You'll also notice a metal cylinder sticking out of the seat. Some customers have ground this down and some customers have just left it. Nobody has reported it interfering with the jump seat yet.
A picture of the holes is below. Whether you have a 1999 or a 2010, the holes are the same.