If you use the aluminum outdrives and AE screw and nut, you have to shave the T-nut down to fit in the outdrives and you have to drill out the center hole on the shorter outdrive since the hole is not big enough for a 2.5mm screw to fit thru. You also loose the ability to adjust the diff thru the small hole in the outdrive, unless of couse you groove the head of the AE screw. This way it will lock the screw with an allen key thru it so you can still adjust the diff with out popping off the rear ball cup.