I have been curious about adding one to my F350. Noticed some trucks come with them, mine did not. Pulling with the truck I have not felt the need for it with the stiff suspension, but you don't miss what you've never had.
TV: 2013 F350, Lariat, 4x4, CC, LB, 6.7L Powerstroke
FW: 2013 Jayco Eagle Premier 361 REQS
Additions: Onan 5500W LP Generator, Surge Guard TS,
.......Roof Satellite Dish, Vent Covers, Bedroom Vent Fan,
.......Rear Reciever, 12V DC Outlets (6), 320W Solar & Controller,
.......4 Lifeline AGM Batteries (600 Ah @ 12V),
.......Stereo Upgraded, Interior Speaker Upgrade, Amp