We have a Northstar Igloo on a 2013 F350 diesel crew cab SRW and are very happy with it. The Igloo will be heavier than the Liberty but I'd still go with the 1 ton. Gas or diesel is your choice. We pull an 18,000 pound 5th wheel once in awhile so diesel was the obvious choice. We had the truck for three years before we got the Igloo so if I was to do it over I might have gone with a dually but so far the SRW has handled the Igloo just fine. The 6.7 diesel has been bullet proof so far. The Northstar is a quality unit. You'll be pleased.