No. Pre 2016 emissions are not compatible with the DSS and a lot of 2016 coaches are on 2015 chassis so even they have 2015 emissions. And it’s not just the plug difference which was the initial problem adapting the DSS (designed for Spartan) to FL. That issue was easily solved because it was just the plug and the electronics were essentially the same.
But pre-16 systems are a lot more on the analog side of things (an electronics expert I am not). The good news is that the pre-16 system don’t have the QUAL (DEF quality) sensor which was a weak link in the system causing headed failures for several years. Also the level sensor in the pre-16 systems is mechanical (a simple float) so it is often to easy to solve errant “low DEF” issues which would otherwise derate you and could leave you stranded.
So the short answer (guess I could have just started with this) is that while the DSS won’t work for you, you also don’t have that much need for it. Below is a link to the TSB on the FL DEF header tank level issue and the typical fix. I’ve also seen accounts of people flushing the tank several times with hot water to clean the float assembly and resolve the issue without pulling the DEF header.
Another common problem with pre-16 DEF headers was tank heater valve failures. When the valve fails, it fails in the open position (dumb engineering decision) so if it opens errantly it cooks the DEF at engine temp which degrades it to the point that it no longer functions in the SCR so once again, you DEF temp warnings and/or low DEF warnings when your tank isn’t empty. The fix is to either by-pass the tank heater (since you probably don’t need it anyway) or if you plan to operate in sub 12° F weather (unlikely) you can install a manual valve on the supply side. There is ample info on this available and it is a simple cheap fix.