Installed a set of these on my full size non-factory queen bed. Huge improvement, but am now planning to add a 3rd shock in the middle. The new mattress is quite a bit heavier than the (garbage) mattress that came with my trailer. As a result, it lifts fairly easily, but just barely holds it. I would post some pics, but trailer is in winter storage. Plan on lots of extra reinforcement where the shock mounts to the "box" frame below the bed, as they are usually pretty flimsy. "Screw and glue" any wood that you are using to greatly increase the strength of the mounts.
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2015 Forest River Vibe 268RKS being pulled by a 2010 F150 Lariat 5.4l, 3.73 axle Super Cab, Max Tow with 11,300 lb tow capacity , Equalizer 4 point W/D hitch