Sorry, Brian, I'm not much help but I wanted to welcome you to Colorado anyway. I know that you are in the "basic" emission testing area and not the "enhanced" emissions area. I don't know if they are going to look for cats or not though. I don't know if anyone else here can shed some light for you, you may have to call Weld county.
I hope you don't live too close to the Monfort plant!
It's nice to have another Defender in Colorado.....