I recently purchased a 21 Yukon Denali. This one did not come with the “tow package” I know this one does not have the new air ride suspension. Can someone tell me what my rear suspension is? Do I have air bags in the rear. I’m asking because I tow with it and it seems to squat some in the back. Can I add air bags into the back of this model to get a little bit more of a lift?