loud noise when in park in engine on 1999 Ford Expedition

my engine makes a loud knocking noise when in park and when I shift to drive it stops but when driving my 4x4 sensor light flashes when driving and my radio goes in and out

by in Appleton, WI on March 19, 2014
2 answers
ANSWER by , March 20, 2014
The knocking noise is just a guess from not hearing the noise, possible torque convertor nuts or flywheel. Electrical needs to be diagnosed.
ANSWER by , March 20, 2014
scan trans codes or get a free diag and est from aamco then post results b4 repairs are made