My automatic 2006 2500 24V with the 48 RE automatic started sounding nasty in park, neutral, and drive sound goes away in reverse sounds kind of sounds like a rod nock but it goes away in reverse and after I get over 1500 rpm, it made this sound slightly a few months ago and then whent away but it sounds like it’s here to stay this time, any ideas where to start would be greatly appreciated. (Yes it has proper amount of trans fluid and it’s not burnt or discolored) no check engine light and no transmission codes yet. Does rock forward when first put in drive with foot on the brake but I always thought that was normal.