Hello. I have a 2011 el 4x4. I put the rancho quicklift on the front and want to put the same on the back but it states they can't go on. Is it possible to install them? What are my other options to get a small lift in the rear? I love the quicklift for the front. It just really sags now when I pull something. Is there a airbag kit out there for it. All my research has come up empty. Thanks in advance.