rattle noise?

i have a noise that comes from what i think is the transmission/converter but near the back of the engine. it sounds like an empty rattle can almost and is really scarring me as this is a brand new 351 w i jsut put together inside my brand new freakin engine bay. could this be the tourque converter i didnt pour tranny fluid in the converter when i installed it so i dont know if that makes a difference but everything else is fine. my oil preassure is around 60-70 at idle i dont know if that is too high or what but it is a brand new motor with less than 15-20 miles on it so yeah. its a 351w with headders car has power steering but we pulled the cylinder down and noise got quieter. the tranny cooling lines are close to the oil pan but that doesnt make much of a difference it gets a little quieter when i grab them. when i rev the motor up the sound goes away at around 2-3ish and up and the motor jsut purrs and sounds great at that speed. the noise is also there when the tranny is in any gear, park, reverse, neutral, and drive. the motor does shake quite a bit at idle but the mounts are new and everything. note that it only makes this noise when the motor is at idle and shaking. anyone i am in desperate need of help. could my converter and tranny have gone south? need help.

thanks,
tommy

yes i have driven it like this but only to the muffler shop bout 5 minutes away to get my exhaust welded on. when the engine rocks at idle the headers would rub and hti the power steering cylinder. i fixed that but it now sounds like a rattling from the converter or near the back of the engine/transmission.

hehe ill check all that stuff
thanks guys.