Unless you go aftermarket, 4.10 is about as good as it gets on the corporate rear diff. I think some of the guys were talking about 3.90 & possibly a 3.73 ratio available.....but expensive. You could look around for a dana 60 with a 3.54 ratio, & swap it in to get a better all around gear. as far as posi unit, try jacking up the rear, & turn 1 wheel.....if the other turns the same direction, its posi.....if it turns backward, then its open. Hope that helps ....crazy AL
