I recently got a '91 YJ with a 4 banger. It is pretty worn (170,000 miles) but still in working condition. It has 32x11.5x15 tires and what looks to be a 3" shackle lift. When driving it "creaks" on the passenger side and it sits about 3/4" lower at both the front and back on that side. I just put new Ranchos all the way around and it is still that way. What could be the issue?