i believe you're talking about the slideout adjustable braces.
they have two plastic covered "feet" on each end of a threaded rod.
most owners don't use them. we don't on short trips but do if we're driving on windy mountain roads, where lateral forces may stress the slideout.
i would contact FR parts dept. and find out how much a pair would cost, if you feel the need for them.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package