smelly catalytic converter?

Well things just got weirder. I climbed under to have a look and it doesn't have a cat? I naturally assumed it would and that smell is usually from a bad cat. It's a turbo cummins, didn't they have cats? I'm guessing no so now what, is the smell just coming from the muffler?

Rotten egg smell is usually Sulphur.

Sulphur in Diesel Fuel Regulations in Canada

http://www.ec.gc.ca/energie-energy/default.asp?lang=En&n=7A8F92ED-1