The rattling is beyond loud. Over powers engine and exhaust noise.

 

You're gonna have to buy yourself a cheap stethascope (about $3 at Harbor Freight) and pin point where it's coming from. Otherwise we are completely shooting in the dark, since it could be so many different things.

 

Have you pulled the valve cover? I would pull it and check for collapsed lifter or shavings from a cam bearing or other worn areas. Even try spining it over by hand a few times to see any funny movement on the rockers or noises.

 

Hey, sorry I haven’t been on here in quite some time. Have a different email so I wasn’t seeing the posts here.
Probably not the news you want to hear, but surprisingly mine ended up being a rod bearing. I tired everything hoping it was something topside as that’s what i really thought it sounded like. replaced lifters, swapped injectors etc... Hopefully that’s not the case for you or you’ve figured it out by now. Good luck man!

 

:d