Are you certain you're getting the white lithium grease all the way through where the shaft passes through the rubber boot? One application on my TJ's steering boot was enough to cure the squeaking the last ten years I owned it. If you're using enough good quality white lithium grease there, I just dunno what to tell you because it permanently stopped mine from ever squeaking again. Maybe a heavier bearing grease? But heck, I just can't figure out why the white lithium isn't doing the job if you're using enough & it's good quality.