grinding sound up front???????? help

ok so hears my problem i have had this damn noise for a while now, it wasnt to bad at first but i put some toy tec diffretial drop spacres on and the noise is alot louder, so i fig it was my brakes i had the front pads changed rotors turned, had the rear drums turned and new pads and kit, and still this noise is there its like a grinding noise but not so muchgrinding more like a howling grinding noise if that makes any sence, and so i put it in 4wd yesterday and the noise stoped it was gone put it back in 2wd and there it was , can someone please help me

oh yeah 05 tacoma access cab, 4.0 manual, trd package