Engine rattling sound, please help!!

[bob97]

I have a 97 7.3 PS, automatic with 14800kms. It's all of a sudden developed an interior engine rattle at an idle, or better when not under load. It sounds like it is at the front of the engine and sounds like you have got a couple of rocks in a coffee can shaking them around. If you put the truck in gear, the rattling stops. If you are accelerating you won't hear the noise until you have reached speed and the engine is no longer under load. My mechanic is the best PS mechanic around here, and he has never heard this noise before.

I have read a couple of posts in which people have mentioned torque converters or injectors as possible causes. Can anyone verify these as causes? Does anyone have any advice or experiences they could offer before we start tearing it down?
Thanks for your help, I really appreciate it.