Hi Pam,
I think we have the same detector?
attached is the link for what I just purchased. The original didn't have the co detector. I didn't even have to take the anchor plate out, snipped two wires, one red, one black and connected same, and slipped back onto anchor plate.
The price is Canadian, I didn't pay that, mine was $95. I didn't have the space to buy a different brand. Notice the on the face it is good for 60 months from date of install.
They come in a I think 3 different colours.
Good Luck
https://rvpartshop.ca/product/safety...25-741-bl.html