i have just done the same thing fella!although i fitted a 4x4 rail as well!i think the 2wd reg will not fit onto the 4x4 rail!but you can modify the 2wd rail and reg to fit the 4x4 inlet by cutting one of the locating lug off and moving it into the right place and i think you have to make up a bracket for the regulator to fit onto the plenum!i think there is a 4x4 rail/regulator for sale on her tho chap