No difference on the road in 2WD. Love it in 4WD. I can feel it pulling me up obstacles like a cat climbing a tree. I don't remember what the part number was. The gear ratio will make no difference, as this replaces the spider gears inside the differential. I had it installed at ProGears in Kearny Mesa on Ronson Road: https://www.progearaxles.com/ They did a great job.