DocT

Hi I have a '93 Subaru Legacy AWD. It just started having a loud knocking/clanking sound when the vehicle is moving and not accelerating. It does this in any gear or neutral as long as the vehicle is moving and there isn't a load on the transmission. When you accelerate the sound goes away until you get off the gas. Car has 170k, but I have had it for about 1k. My son drives it so I don't know if this came on suddenly or worked its way up. The sound goes faster if you are going faster and slower if you are going slower. Where should I be looking? Thanks in advance.