The #2,4 and6 injectors are non operative in my '04 f450(tank lining plugged my pump and starved my injectors),chiltons are rather vague as to the location of the oil and fuel drain plugs in the head and as im not looking forward to hydrostatic lock, id like to do this right the 1st time.oh,and there is talk of a injector removal tool,do i really ...need this?a little direction would be greatlly appreciated.