We also just installed new detectors in our 2017 3710FL. We went with the 10 year battery, combination smoke/CO detectors.
https://www.lowes.com/pd/First-Alert...ery/1000456445
We only had a CO detector in the bedroom and a smoke detector in the living room. Replaced the CO in the bedroom with the new CO/smoke detector, and placed a second new CO/smoke detector next to the existing one in the living room.
Doing some research, I found that "they" recommend have two different smoke detectors - ionization and photoelectric. The old one was ionization and the new one is photoelectric which is why I kept the old one for now - it hasn't started chirping yet.