what is the difference betwen the longfield and the newfield 27 spline axle and birfield ? If you were to buy upgraded axle and birfield which would you buy and why. I am trying to decied on which to buy. Currently I am running 36" IROK with a 22Re and dual transfer case 2.8 and 4.7 with 4.10 rears. The front and read are both locked. Thanks