So heres what I would do if I was you. See if anyone in your area is parting out a Rainier V8, Saab 9-7x V8, Envoy V8, or Trailblazer V8.
From what I am seeing, 5.3 or 6.0 use the same Y-Pipe and cats, and if they are parting them out local to you, and you can install them yourself, or with a...