The first thing to know when looking for a replacement is that you want the "Surface Mount" model. They also make a model that fits into a hole cut into the wall,but this is not what is used in the Roadtrek. Next - the model number of the CO Detector made by MTI Safe-T-Alert that was in my Roadtrek was model 65-540-WT. I learned from the company's website that the WT is for white as it also comes in cream color and that while this model is still listed on the website's sales page as available the model number that I was finding to match the description of this RV CO Detector was different. The model number was showing up on Amazon and at other sites selling these was MTI Safe-T-Alert 65-541- WT. I called Safe-T-Alert to ask. The 65-540 model is discontinued and the replacement for it is the 65-541. This is an upgraded model with an end of life alarm that will alert you to when it needs to be replaced - in five years. The specs and size of this newer model is exactly the same as the older model. Here is a link to the manual.
Before undertaking this job I wanted to see how this unit was installed. There are two screws holding this to the wooden panel below the rear passenger side cabinet in the Roadtrek. I removed those screws and the unit came down with two wires attached and disappearing into the inside of the unit through a small hole in the upper middle of the back. The black and red wire went into a hole in between two cushioned fabric panels in the Roadtrek.
I was hoping that the case of the unit came apart and that inside there were terminals to take off and reattach the black and red wires. That would have been too easy a design. My thoughts of a quick an easy installation requiring just a screw driver were gone. No, the connections to the 12 volt power source that this CO Detector must be connected to is inside that small parting of the cushions forming that little hole. I looked to see if there was access behind where the wires go and it did not look like there was. I put the screws back in the holes and put the unit back up.
I started asking on the Roadtrek Facebook page and had a quick answer from Jim Hammill, President of Roadtrek, telling me that as my Roadtrek is wired differently from most because a different wiring harness was installed at the factory for my DC/AC refrigerator (instead of the standard propane/DC/AC Roadtrek refrigerator) access was not going to be easy and my choices were removing the floor of the cabinet or just removing some screws to make the opening that the wires pass through temporarily larger by releasing one of the cushioned panels - but I would not be able to access where the actual connections were made. The plan no matter what was to cut the wires on the old unit and splice in the new unit which I will get to as we go along here in this article. Others told me this is how they did the job as well - cut the wires and join the new wires to the old. How different this area in my Roadtrek is from others, I don't know, but others that have done the job tell me that they wound up doing just the same as I will describe to you here that I did.
I ordered the replacement CO Detector from Amazon.com. The price was the lowest that I found - $54.95 plus $7.50 shipping. There was a rebate coupon good until September 2013 that came with the unit to mail in with part of the package to get back $10. Be aware that I found various prices for this same unit that went from here to over a hundred dollars. Shop around for it. The unit arrived in less than one week. This is what the package looks like removed from the shipping carton. If you look in an RV shop for this, this is what you will see.
I next went shopping for connections. The connections suggested to me were crimp on snap connectors (sometimes called "bullet connectors" and they are available at Radio Shack stores for $2.49 for a pack of ten (five male and five female). They come in red and blue. Here is a photo -