My 06 f350 is 2wd and only has a sway bar in the front. Was the rear one an option or is it only for 4wd??

Would this be something to add if towing an overhead camper? or just simply not necessary of you have one in the front already?

 

Not sure about '06 but it was part of the "Camper Package" in '08 - mine came with the "Trailer Towing Package" but not the "Camper Package". The first time I drove it with my Lance Camper on board, I really didn't like the "squirrely feeling" so I checked on the Ford Rear sway bar. The price from Ford was more than I could buy a Hellwig for. I ended up getting a 1.5" Hellwig and have never looked back. It handles great, changing lanes fully loaded is a breeze and at highway speeds, I feel totally comfortable and safe! Just Google "Hellwig Sway Bars" or Hell, here's where I got mine: 1999-2010 Ford F250, F350 Super Duty SRW - REAR Big Wig Sway Bar - 7268 | $309.95

 

The camper package is made for slide in campers. With all that weight up high you need the sway bar for stability. Sway bars are not for 4wd, they actually keep your axle from articulating fully while off roading. That is why serious off roaders will actually dis-connect sway bars when they hit the trails. For on road there is no better way to make a vehicle stable. A rear bar would be a great addition for you.