Muffler sometimes makes rattling noise, but goes away when in neutral or park.

What is your question?

Took it to midas, they change several gaskets. The truck ran nice and smooth for about a month then the noise came back. So took it back to Midas they said this would keep happing and recommended just welding it(no guarantee that this would work he said) So, I said lets try it. It didn't work still makes the same rattling noise. They now say to fix the right way will cost 700 to 900 dollars! This on top of the gaskets and such I've already had them do to the tune of about 400$!