converter-bottom end rattle?

[poppop]

I have a 90 F350 with an E4OD.I have a bad rattle either in the back of the engine or the converter.If I start the engine I have this rattle like I have never heard.When I throtle up the rattle goes away.If I shut the engine down and start back up no rattle untill I drive.I had this problem with the first trans and thought I had a trans problem.I replaced it with a junk yard trans and have the same problem.I am thinking maybe both trans had bad converters.How can I know the converters bad before I change it again.Thanks-

 

[schoelta]

Make sure that you don't have a cracked flex plate.