If your TeamForge 16.3 site runs on a RHEL/CentOS 6.8 server, you can upgrade to TeamForge 16.7 on the same server.
While it's desirable to upgrade to the latest RHEL/CentOS version, one of the advantages of upgrading to TeamForge 16.7 on RHEL/CentOS 6.8 is the ability to run Black Duck Code Sight on RHEL/CentOS 6.8. Remember, Black Duck Code Sight 2.1.3 has no support for RHEL/CentOS 7.2.