The XPR series has a GOB (General Option Board) that can be programmed for different functions. One of those functions is to enable analog LTR trunking (which is sold and setup by Scholer Johnson - SJi) I believe that would still be available on an XPR7350, but I've got no facts to back that up.
There's also a Digital trunking option - Capacity Plus or Capacity Max. Capacity Plus is a single site trunking solution, Capacity Max is multiple sites linked together. The XPR7350 should do Capacity Plus out of the box, but Capacity Max might require some EID enablement magic, if it would work at all. The "e" series should do Capacity Max.
On top of all that, there was also a trunking option called Connect Plus which is on the way out.
What kind of 500 MHz trunking do you require? Most trunked 500 MHz systems that I'm aware of were either LTR analog systems, or Public Safety systems.
Confused yet?