ANOYING NOISE on 1999 Ford F-150

my f-150 has a anoying noise that sound like if it was the lifters but it sound around the transmision area and only makes the noise when it is in drive and is not moving.I have already rebuilt the whole engine and replaced the converter, the catalytic converters and the flow wheel but the sound still i want to know what could be the problem..

Asked by for the 1999 Ford F-150