Yes, I have replaced jackknife couches in two gasser MHs. I put recliners in place of the couch. Check dimensions of new couch to insure it will fit through narrow RV doorway. You will need to bolt it down to the floor and possibly install seat belts depending on your travel needs.
Cost is your choice of new furniture minus what you get on CraigsList for the old couch. Done this twice, no regrets, greatly increased comfort.
George R. - Fulltiming since January '03
2007 Newmar Mountain Aire 3991
2012 Chevy Malibu LT1