Mazda Repair: Catalytic Converter, mitsubishi mighty max, wreaking havoc

Question
Recently I had the catalytic converter replaced on my 1987 Mitsubishi Mighty Max Pick Up truck.  Shortly after replacement, there's been considerable "vibration type noises"(rattling) coming from the area of the converter.  Are there any parts or places on the converter itself that requires adjusting?  Upon hitting the converter with my fist, I hear noises.  Is this a common problem?  What would you suggest?

Answer
Option A: Catalytic converter heat shield is loose or has bits of rocks and or rust stuck in it. Gets very annoying and makes an otherwise nice vehicle sound like a piece of crap.

Option B: The catalytic converter installed was injured prior to installation and is now broken internally and will be breaking up and wreaking havoc on the rest of the system.

Solution for all the above:

Take it back to the shop that did the work and ask them to fix it.
If this is not possible, take it to a Midas or Meineke and have them fix it. This needs to be addressed to ensure that Option B is not the problem. If Option B is the problem it will need to be fixed by the shop that did the work under warranty. This is not something they did wrong in ether case A or B, but simply things that can crop up when doing exhaust work.

Regards,

John