We just had a onan/cummins marquis gold 5500 LP installed in our 2009 bighorn 3580RL. It runs both ac's and rest of RV just fine. Also, it is very quiet in the bedroom which is just above the gen set. We bought it from a firm called Colorado stand by (
www.coloradostandby.com ) shipped to Texas, cheaper than we could buy it locally. Hayes RV in Longview, Tx did the install. Good luck and God Bless ya, Al W