ntp- Can you tell who is getting a time stamp from your server?

Tru64 5.1A PK56

Hello managers,

I am decommissioning a Tru64 5.1A DS20E server. All apps
are off and it's pretty quiet.  This server was our
main NTP server at one point. Most other servers should be
pointing to other time servers now, but I'm sure there are
probably some still pointing to this server. Is there any
way to tell who's coming on the host to get a time stamp?
Perhaps tcpdump and look for certain traffic? Or maybe
there's another way to see if your NTP server is active?

Thanks for the help.