I suggest you get with the system administrator and go through an approved vendor to acquire exactly what you need then. That'll guarantee you end up with a reliable radio that will work right from the beginning without any problems.
That part. And since the radio will be used for life safety, make sure it has been properly vetted by your radio shop/support team if it is a used radio. You are entrusting your life and the safety of others. Buying a used radio off eBay or any unknown source is a gamble.
There are many hacked up, jacked up, junk parts garbage pail radios from second hand sources. They may work fine for hobbyist or hams, but no way I, as a public safety systems support person, would EVER allow one on our system as the liability is too high.
Trunking radios may require specific options your system management uses. The advice to consult with (and go through their authorized procurement sources) is sound.