Anyone towing or hauling heavy on a regular basis with their F150 has probably noticed that their rear ends tend to sag a good bit, even if you're not pushing your tongue weights or GVWR. To help keep your F150 level when loaded, you'll need an air spring kit. Air springs are heavy-duty rubber springs that you fill with air when you're loaded in order to keep your truck under control when you're hauling along. Also take a look at our F150 Tuners to get more power for your tow rig. Ford F-150 Fitments: 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ford F150 Submodel Fitments: FX2, FX4, King Ranch, Lariat, Limited, Platinum, STX, XL, XLT. Some Exceptions apply, please see individual product pages for specific fitments.