i had the tsb performed a couple months ago for the condensation in the intercooler that made the truck shudder and misfire. dealer told me the cats are o.k. and dont need replaced. now i am now getting a vibration and a drone sound at 1800-2100 rpms in 6th gear. a drone is like a hollow out sound that is annoying to the mind. should the cats have been replaced? maybe they are falling apart inside?

 

Seems odd that you would be getting that kind of noise only from a failed CAT. I also had the same TSB performed on ours without replacing the CAT, and no problems since.
I think that when a CAT fails, you are going to get reduced power (plugged CAT), and if there is a way you can get the emissions checked (I think that they can even do that with the under dash plug-in port) and that will quickly tell you if the CAT(s) are working up to snuff.

 

My dealer isn't taking any chances and has ordered Cats and IC as soon as I mentioned a slight shudder that happened only once in the last 6000 miles.

 

i can get an emissions check. my buddy has a garage. my inspecion and emissions runs out in june.