I am using the XD60 rear axle and ProRock 44 front axle on 37 inch Nitto Trail Grapplers. I love the ease of maintenance, no more RTV to deal with. The strength is definitely there with a stronger and more robust rear differential cover. Last week, my wife dug the rear pumpkin into the dirt and drug it quite a ways. Not a single scratch. Very impressed and happy. Thank you Dynatrac!!